1. A textile dyeing system using SC-CO2 comprised of a dyeing vessel (7) for dyeing of textile fibre/fabric form, consisting of various subsystems such as CO2 gas cylinder (1) connected to condenser (2) for liquefaction of CO2 and high pressure carbon dioxide pump (3) for pressurization; two heat exchangers to raise temperature connected to dye solublisation vessel and dyeing vessels

2. The textile substrate in fibre/fabric form is placed in the textile holder of the inner chamber. SC-CO2 is passed from inside/outside and top/bottom inside the chamber to achieve dyed substrate.' > . v

3. The SC-CO2 dyeing vessel withstands 330 pressure bar and temperature of 130 °C.

TITLE: SUPERCRITICAL CARBON DIOXIDE (SC-C02) TEXTILE DYEING VESSEL FOR DYEING OF TEXTILE SUBSTRATE IN FIBRE/FABRIC FORM
Field of Invention:
The present invention relates to Supercritical carbon dioxide textile dyeing vessel. The vertical high pressure vessel is a waterless dyeing vessel using supercritical carbon dioxide for dyeing of textile substrate in fibre/fabric form. The SC-CO2 dyeing vessel has internal chamber with perforated rod to facilitate inside/outside and top/bottom circulation of dissolved SC-CO2 dyes for uniformity in dyeing. This high pressure dyeing vessel can be pressurized till 330 bar and goes upto temperature of 130 °C.
PRIOR ART
Imparting colour on textile substrate is an important factor in textile dyeing. Dyeing is the process of adding color to textile products like fibers, yarns, and fabrics. There are various methods and machines available for the textile dyeing. Some of the popular categories of textile dyeing machines are Jigger dyeing machine, Winch dyeing machine, Jet dyeing machine, etc. Textile dyeing is conventionally carried out using water as media. Huge amount of water is required to carry out dyeing using these machines. This ultimately generates waste water after process of dyeing. This waste water creates water pollution problem, to which installation of wastewater treatment plant becomes necessary. This leads to additional capital expenditure to the Textile industry.
Thus, research is going on for more than a decade in search of new environmental friendly technology for textile dyeing. This ultimately has resulted to discovery of using supercritical carbon dioxide as media for textile dyeing. This technology is a waterless technology.
Supercritical carbon dioxide
Supercritical carbon dioxide is a fluid state of carbon dioxide where it is held at or above its critical temperature (304.25 K / 31 °C) and critical pressure (74 bar / 1073 psi). Under these described conditions the distinction between gases and liquids does not apply and substance can only be described as fluid, which behaves like liquid in supercritical stage even though it is in gas phase. The density is equivalent to liquid so it has got the solvating power. One such fluid is supercritical carbon dioxide. Carbon dioxide is found abundant in nature; hence it is the most preferred supercritical fluid for carrying out the extraction process.
Supercritical carbon dioxide is an established process in the technology of extraction of essential substances from the extractor. The technology is commercialized and the industry is using this technology. Supercritical carbon dioxide is used as a solvent in supercritical fluid extraction. The substances are immersed in supercritical carbon dioxide in a pressure chamber at 73 to 300 atmospheres. After a thorough soaking for around ten hours, the pressurized C02 containing dissolved substance is removed from the chamber which is returned to atmospheric pressure, allowing the C02 to evaporate. The extract is removed from the C02 using charcoal filters and the C02 is recycled for use on another batch. When the extraction is complete, the pressure is

reduced to ambient and the carbon dioxide reverts to a gas, leaving no residue. This process has the advantage that it avoids the use of potentially harmful substances. This method is applicable for extraction of oil, waxes, fragrance, medicine, coffee, etc from various substances. Supercritical carbon dioxide is also used instead of PERC (perchloroethylene) or other undesirable solvents for dry-cleaning.
Supercritical carbon dioxide for textile dyeing
The supercritical carbon dioxide (SC-CO2) is an established process in extraction of food, flavour, pharmaceuticals, etc. SC-CO2 is now being explored for textile dyeing too. In case of textile dyeing it is still in developmental stage. The SC-CO2 textile dyeing process is contrary to extraction process, wherein the dyes are not extracted rather it is deposited on the textile material. However, no appropriate dyeing vessel is being developed to carry out dyeing of textile substrate.
Existing SC-CO2 textile dyeing vessel:
Research is ongoing in developing the process of dyeing using supercritical carbon dioxide along with equipment for dyeing. Dyeing vessel is a critical area in the development of the SC-CO2 dyeing of textile. Few of the published patents abstracts as given below are available; however no such dyeing vessel has been established and also no such commercial SC-CO2 dyed product is available in market.
High-pressure dyeing vessel in supercritical carbon dioxide dyeing process CN 2350412 Y, Chinese patent 24th Nov 1999
The high-pressure dyeing vessel in supercritical carbon dioxide dyeing process is composed
of a dyeing liquid guiding pipe, a multi-hole sleeve pipe, central baffle plates, edge baffle
plates, basket caps, a guiding pipe nut, a dyeing liquid guiding pipe inlet, a dyeing liquid
outlet pipe, a vessel body, a vessel cap and a sealed fastening ring. Because dyeing liquid
contained in supercritical carbon dioxide enters the high-pressure dyeing vessel under high
pressure and temperature and flows and passes through a yarn ball from center to periphery
and from periphery to center in the vessel, the high-
pressure dyeing vessel in supercritical carbon dioxide dyeing process has thorough dyeing and no waste liquid and is a newest dyeing vessel. The high-pressure dyeing vessel is connected with 3 to 8 dyeing baskets in parallel, high-pressure dyeing baskets can also be connected between pipelines in parallel, and intermittent dyeing is changed to continuous dyeing, so that productivity is increased, and meanwhile, each component of the kettle is tightly connected without being welded. The utility model has convenient dismantling, disassembling and assembling. The central baffle plates and the edge baffle plates in the dyeing baskets are generally and respectively 4 to 10, and the inner part of the high-pressure dyeing vessel is connected with 3 to 8 dyeing baskets in parallel.
This SC-C02 dyeing vessel describes about the dissolution of dye in SC-C02 and only for dyeing yarn.

One kind of using supercritical carbon dioxide fluid fabric dyeing apparatus and method CN 101824716 B Chinese Patent published on 25th April 2012
A method for improving the fabric supercritical carbon dioxide levelness method and apparatus. It is the use of the outer and inner layers composed of a special seamless warp axis, and the outermost layer of the winding packages, seamless weave fabric mesh cloth cylinder and the stationary fluid circulation control staining time than other parameters in order to achieve supercritical carbon dioxide fluid evenly piece dyed fabric dyeing. This method uses a rational structure of the beam pattern, the fabric roll form and process conditions, and therefore can dissolve the dye-containing supercritical fluid through the wound fabric evenly, reducing the fluid flow during the cycle the pressure loss of the non-uniform, sudden change in the flow path, and the unevenness of fluid circulation, the piece dyed fabrics improved leveling effect. Method of the present invention has the equipment and process technology is simple, easy to operate, efficient and energy saving advantages.
This SC-CO2 dyeing vessel can dye only fabric. This doesn't contain inside/outside circulation of SC-CO2.
Supercritical fluid dyeing machine
CN 101760914 A Chinese Patent published on Is' Feb 2012
A supercritical fluid dyeing machine, which includes, a horizontal type cylindrical dyeing kettle, a magnetomotive cloth lifting wheel, a spray cavity, a wave-shaped cloth guide passage in the dyeing kettle, a heat exchanger, a dye kettle or/and an entrainer kettle and a circulating pump to form a dyeing circulation system; and both ends of a fan are respectively connected with fluid outlets under the spray cavity and the dyeing kettle and form a cloth feeding system together with the magnetomotive cloth lifting wheel, the spray cavity and an operating opening. A rope-shaped fabric realizes circulated dyeing under the common action of the fluid in the magnetomotive cloth lifting wheel and the spray cavity, and the fluid in the dyeing kettle carries out forced circulation by the circulating pump. The dye and the fluid can be recycled by separating and recycling system are clean to achieve the requirement during color changing and dyeing.
This SC-C02 dyeing vessel is a horizontal type vessel and can dye only fabric. This doesn't contain inside/outside circulation of SC-CO2.
Dyeing of fibers using supercritical carbon dioxide and electrophoresis
US 8439982 B2, US Patent, 14th May 2013
This apparatus is for dyeing textiles that includes intermixing a dye with supercritical carbon dioxide (sc-C02) to form a dye solution and immersing a fabric in the dye solution. It includes applying an electric field to the dye solution to cause charged particles of the dye solution to separate and cause the dye to diffuse into the fabric. The apparatus further includes a cathode and an anode that produce an electric field in the dye solution that causes charged particles of the dye solution to separate and cause the dye to diffuse into the fabric.

This SC-C02 dyeing vessel describes about the dye mixing vessel and dyeing of textiles in one vessel itself. This doesn't contain inside/outside circulation of SC-CO2.
Supercritical carbon dioxide cheese dyeing kettle and waterless supercritical carbon
dioxide cheese dyeing method
CN 102787459 B, Chinese Patent on 15th January 2014
The method relates to a cheese dyeing in supercritical carbon dioxide and dry autoclave reactor dye staining method. Carbon dioxide fluid inlet is connected with the dye pot. Before dyeing begin, the cooling system is opened, so that the tank pressure drops to 3 ~ 5MPa, tank level rose to 400 ~ 430mm, dyeing pot pass into carbon dioxide gas, fluid carry the dye into the dye pot cylinder. Heating system is turned on and the temperature reaches the dyeing temperature. The system pressure is raised to open the pressure dyeing, for staining. While dyeing part of the carbon dioxide fluid outflow through the central axis from the inside out, from the outside of the bobbin yarn dyeing gradually to the cheese inside; out of dyed yarn bobbin from the inside. Upon completion of staining, the outflow of fluid is the outlet of carbondioxide. During dyeing process, as the pressure increases, the blade, the structure of the thread means sintered filter pipe starts to rotate, during rotation of the yarn cheese dyeing is achieved. Upon completion of dyeing, the dyeing autoclave is released from pressure by cooling, recycling of carbon dioxide is done and undyed dyes are collected.
This is a cheese dyeing kettle using SC-CO2 and only meant for yarn dyeing Problems and Solutions:
AH the above inventions relate to application of supercritical carbondioxide for dyeing textile. However, more precisely these inventions explain only about the process of dyeing using SC-CO2 technology and not about the dyeing vessel in particular. The above stated SC-CO2 dyeing vessels dye either fibre or yarn or fabric and not the textile substrate in different forms.
Current Status: International
Internationally there are few patents available; however they describes about the process of dyeing of textile fibers using the SC-CO2 technology and not about the SC-CO2 dyeing vessel in particular with inside/outside and top/bottom circulation of the SC-CO2 in the vessel.
Current Status: National
No commercial machine is available for supercritical carbon dioxide dyeing in India, as on date.
Thus, the proposed invention aims at designing and development of prototype of laboratory dyeing vessel using SC-CO2 technology. Dyeing vessel is a critical component/subsystem in the development of the SC-CO2 dyeing of textiles. The designed dyeing vessel is used for dyeing of textile materials in any form viz. fibre/yarn or fabric. The invention is an indigenous design and development with the facility for inside/outside and top/bottom circulation of SC-CO2.

Statement of invention
A waterless textile dyeing machine for dyeing of textile fabric using SC-CO2 comprised of a vertical SC-CO2 dyeing vessel and consisting of various subsystems; a CO2 gas cylinder supplies CO2 gas to condenser which liquefies the CO2 at -12 °C maintained by chiller. The liquefied CO2 pumps through the high pressure CO2 pump to raise the pressure above its critical pressure of 74 bar; two electrical heat exchangers to raise temperature of the liquid CO2 above its critical temperature of 31 °C; a dye solublisation vessel and a dyeing vessel comprises of pressure relief safety valves and rupture disc; a separator to separate the dyes from SC-CO2; CO2 flow meter to control flow of CO2.
The invention comprises of design and development of SC-CO2 vertical dyeing vessel for dyeing of textile substrate in fibre/fabric form. The vertical SC-CO2 textile dyeing vessel consists of inner chamber with perforated rod in centre. The inner chamber assists inside/ outside and top/bottom circulation of SC-C02. Textile material in fibre/fabric form is placed/ wound in inner chamber. The dyeing vessel withstands 330 pressure bar and temperature of 130 °C. The overall SC-C02 textile dyeing system is controlled through digital panel.

Brief description of drawing:
List of figures:
Figure 1 illustrates the view of vertical high pressure SC-CO2 textile dyeing vessel
Figure 2 illustrates the fabricated vertical high pressure SC-CO2 textile dyeing vessel
Figure 3 illustrates the fabricated inner chamber with perforated rod
Figure 4 illustrates the line diagram and flow of the design of SC-CO2 textile dyeing system.
Figure 5 illustrates the whole fabricated SC-CO2 textile dyeing system
Legend to Figure 1
1. Top inlet valve
2. Bottom inlet/outlet valve
3. Left side inlet valve
4. Right side outlet valve
5. Inside chamber
6. Perforated rod
7. Textile material holder
8. Vessel Lid
Figure 1 depicts the vertical high pressure SC-CO2 textile dyeing vessel. The dyeing vessel consists of top inlet valve (1), bottom inlet/outlet valve (2) for flow of SC-CO2 from top to bottom; left side inlet valve (3), right side outlet valve (4) with perforated rod (6) in centre for flow of SC-CO2 inside /outside circulation in inner chamber (5) and the textile material is placed in the textile material holder (7). The vessel lid (8) on the top of the vessel for mounting/opening of dyeing vessel.
Figure 2 depicts the fabricated inner chamber with perforated rod placed inside the dyeing vessel and textile substrate holder
Figure 3 depicts the fabricated vertical high pressure SC-CO2 textile dyeing vessel with inner chamber placed inside the dyeing vessel.
Legend to Figure 4
1. CO2 gas cylinder
2. Condenser
3. CO2pump
4. Preheater

5. Dye solublisation vessel
6. Heater
7. Dyeing vessel
8. Separator
Figure 4 depicts the set-up of the waterless dyeing machine using SC-CO2 textile dyeing vessel, with its various subsystems. The set-up consists of CO2 gas cylinder with atmp pressure 65 bar of food grade quality with 99.9 % purity (1) connected to condenser (2) for liquefaction of CO2 at -12 °C that is maintained by Chiller. The liquefied CO2 is passed through high pressure carbon dioxide pump (3) to raise the pressure above critical pressure of 74 bar. Preheater (4) heats the pressured CO2 to above its critical temperature of 31 °C which converts the CO2 to SC-CO2. SC-CO2 is passed through the dye solublisation vessel consisting of dyes; thereafter SC-C02 passes though another electrical heater to further raise the temperature before passing to the dyeing vessel which is the heart of the SCC02 dyeing system. The textile substrate is placed in the textile holder of the inner chamber. SCC02 is passed from inside/outside and top/bottom inside the chamber to achieve the uniform dyed substrate.
Figure 5 depicts the fabricated set-up of the SCC02 textile dyeing system.

Detailed description of the machine:
Principle
Basic Principle of Supercritical carbon dioxide:
Supercritical carbon dioxide is a fluid state of carbon dioxide where it is held at or above its critical temperature (304.25 K / 31 °C) and critical pressure (74 bar / 1073 psi). Under these described conditions the distinction between gases and liquids does not apply and substance can only be described as fluid, which behaves like liquid in supercritical stage even though it is in gas phase. The density is equivalent to liquid so it has got the solvating power. Thus, it becomes, supercritical, a state of matter that can be seen as an expanded liquid, or a heavily compressed gas.
Supercritical carbon dioxide in dyeing Textiles:
There are three components in the SC-C02 dyeing process —the gas, dyestuff and fiber polymer. The dyestuff is dissolved in the SC-C02, transferred to, absorbed by and diffused into the fiber. During the dyeing of fibers/fabrics, C02 loaded with dyestuff penetrates deep into the pore and capillary structure of fibers/fabrics. This deep penetration provides effective coloration of textile materials. A further advantage of this dyeing technique is that the dye can be easily separated from C02.
The dyeing takes place in following steps:
A. Dissolution of dye in SC-C02
B. Transport of SC-C02 to the fibers
C. Adsorption of dye on fiber surface and finally
D. Diffusion of dye into the fiber takes place
The developed prototype of SC-CO2 textile dyeing equipment work on the same principle

Basic Design of the Invention:
The SC-CO2 textile dyeing systems has various components as i) CO2 gas cylinder, ii) condenser, iii) chiller iv) high pressure carbon dioxide pump v) two electrical heaters vi) dye solublisation vessel vii) dyeing vessel viii) separator ix) CO2 flow meter x) control panel.
1. C02 gas cylinder
CO2 gas cylinder of capacity 30 kg with food grade quality has siphon tube facility to draw CO2 gas(l).
2. Condenser
Condenser (2) liquefies carbon dioxide gas to liquid carbon dioxide. The coolant from the brine chiller (3) is passed through shell side of condenser at -12 °C and gaseous carbon dioxide entering from the tube side is liquefied.
3. High pressure carbon dioxide pump
High pressure liquid carbon dioxide plunger pump (4) is used to generate pressure above the critical pressure (73 bar) of carbon dioxide which enters from the pump from the condenser. The capacity of this pump is 6.5 Kg/hr with a pump speed of 100 stroke per minute (SPM) and discharge pressure is upto 400 bar.
4. Heat-Exchanger-I
Heat-exchanger-I is a pre-heater (5) and heats the liquid carbon dioxide above its critical temperature (above 31°C) to achieve the supercritical carbon dioxide. This heat exchanger is placed before the dye solublization vessel to raise the temperature of SC-CO2.
5. Dye solublisation vessel
Dyes are placed in the high pressure dye solubilisation vessel (6). The SC-CO2 is passed through this vessel which solublises the dyes and passes to another heat exchanger. This vessel is made up of stainless steel 316 grade and withstands the pressure upto 330 bar and temperature of 90 °C. Internal diameter is 40 mm and internal length of 500 mm. Capacity of the vessel is 1 litre.

6. Heat-Exchanger-II
Heat exchanger-II (7) maintains the temperature of dyeing vessel till 120 °C for carrying out dyeing.
7. Dyeing Vessel
Vertical high pressure SC-CO2 dyeing vessel (8) is an important vessel in the SC-CO2 textile dyeing system as it is used for carrying out dyeing of fibres/fabrics in SC-CO2. Dyes are fixed on the substrates in this vessel. The vessel is made up of SS316, withstands pressure of 330 bar and temperature till 130 °C. The internal Diameter is 80 mm and Internal Length of 500 mm. The capacity of the dyeing vessel capacity is 2 litres:
The developed SC-CO2 dyeing vessel has been designed with arrangement for proper placement of textile materials with inside and outside circulation of SC-CO2. The dyeing vessel consists of top valve and bottom valve along with right and left valve for flow of SC-CO2. It consists of inner chamber with perforated rod in the centre and textile material holder to facilitate the proper circulation of SC-CO2.
8. Separator
The undyed dyes are separated as unspent dyes and collected in the separator (9).
9. Control Panel:
The SC-CO2 textile dyeing system is semi-automated though control Panel (10). This control panel controls the pressure and temperature of dye solublisation vessel and dyeing vessel.
The machine control panel houses the following switches
1. The machine on and off switch
2. The temperature indicator switch for heat exchanger-I with digital display
3. The temperature indicator switch for heat exchanger-II with digital display
4. The temperature indicator switch for dye solublisation vessel with digital display
5. The temperature indicator switch for dyeing vessel with digital display
6. The pressure controller and indicator switch of high pressure pump
7. The pressure indicator display for dye solublisation vessel
8. The pressure indicator display for dyeing vessel
9. Emergency switch

Detailed description of the SC-CO2 dyeing vessel
The textile material to be dyed is loaded in the inner chamber of the dyeing vessel and dyes are placed in the dye solublisation vessel.
The chiller consist of coolant made up of 50:50 MEG and water is passed though condenser at the temperature of -12 °C. This coolant is passed though the condenser to maintain the temperature of -12 °C. Then, the 99 % pure carbon dioxide gas of food grade quality from cylinder is passed through the condenser for liquefaction of carbon dioxide gas to liquid carbondioxide. The carbondioxide has a cylinder pressure of 74 bar at room temperature. It then passes through high pressure pump and pressured to generate pressure above the critical pressure (74 bar) of carbon dioxide. The pressurized carbon dioxide is passed through preheater and heated above its critical temperature (above 31 °C) to obtain the supercritical carbon dioxide. The SC-CO2 then goes to the dye solublisation vessel. Dye solublisation vessel contains dyes. SC-CO2 passes through second heat exchanger which raises temperature above 90 °C till 130 °C. SC-CO2 passes through the dyeing vessel containing textile substrates. The textile substrate is placed in the textile holder of the inner chamber. SC-CO2 is passed from inside/outside and top/bottom direction in the inner chamber of dyeing vessel. The inner chamber consists of perforated rod in the centre surrounded by textile material holder.
The dyeing is carried out at 250 pressure bar with temperature of 90 °C with constant flow of SC-CO2 for one hour. The temperature and pressure is maintained with the control panel system.
Advantages:
The quantifiable benefits of the dyeing using SC-C02 dyeing method over the conventional dyeing are as below:
The designed and developed dyeing vessel dyes the textile material without using water. As no water is used for dyeing hence no water pollution
Uniformity of dyeing material using inner/outer and top/bottom circulation of dyes. The dyeing vessel is especially for dyeing textile material in fibre/fabric form.

CLAIMS: We claim:
1. A textile dyeing system using SC-CO2 comprised of a dyeing vessel (7) for dyeing of textile fibre/fabric form, consisting of various subsystems such as CO2 gas cylinder (1) connected to condenser (2) for liquefaction of CO2 and high pressure carbon dioxide pump (3) for pressurization; two heat exchangers to raise temperature connected to dye solublisation vessel and dyeing vessels
2. The textile substrate in fibre/fabric form is placed in the textile holder of the inner
chamber. SC-CO2 is passed from inside/outside and top/bottom inside the chamber to
achieve dyed substrate.'
> . v
3. The SC-CO2 dyeing vessel withstands 330 pressure bar and temperature of 130 °C.