|Title of Invention||
A PROCESS FOR THE PRODUCTION OF CARBON BLACK
|Abstract||A process for the production of carbon black comprising burning a fuel with preheated air in a reactor to obtain an off-gas containing carbon black particles, hot gases and steam, quenching the reaction with a cooling fluid to obtain an effluent, subjecting the effluent to a step of cooling by allowing the additional heat of smoke to dissipate into the atmosphere followed by a step of further temperature reduction by spraying with a second cooling fluid, and purification of the smoke, collecting the carbon black from the smoke, subjecting the same to pulverisation, densification and drying to obtain the carbon black.|
|Full Text||THE PATENTS ACT, 1970
'A process for the production of carbon black"
HI-TECH CARBON, A unit of Indian Rayon & Industries Ltd., Junagadh
Veraval Road, P.O. Veraval 362 266, Gujarat India.
The following Specification Particularly describes invention and the manner in which is to be performed.
FIELD OF INVENTION
This invention relates to a process for the production of carbon black.
BACKGROUND OF THE INVENTION
Carbon black is used in the manufacture of various commodities such as inks and paints. However, a primary application of carbon black is the rubber industry, and particularly with respect to tires used in vehicles, which may contain 30 to 90 pounds of carbon black per 100 pounds of rubber. The carbon black reinforcement is probably the most important item contributing to the long life of the tire. Without carbon black, the development of the automobile would have been drastically retarded.
It has been figuratively stated that an automobile rides not on rubber, but a carbon black, with the rubber serving merely to hold the carbon black together. This statement refers to the greater durablility, which is imparted to a tire through its carbon black reinforcement The natural rubber automobile tires in use before carbon black was found to be an essential ingredient in rubber compounding were limited to about 3000 miles of wear. However, certain radial tires currently have estimated lives of 50,000 miles or more.
Early research in carbon black resulted in the development of the first successful continuous process for production of reinforcing carbon black from oil. The oil furnace process began to displace gas channel and furnace processes immediately,
primarily because of the black's unique ability to reinforce the synthetic rubbers
being introduced at the time and subsequently, carbon recovery efficiencies of upto 65% compared with only three to five percent with the old natural gas process; and with steady state continuous operation, a more uniform product than ever before could be produced with controlled shifts in known operating variables, a wide
spectrum of properties is possible.
OBJECTS OF THE INVENTION
It is therefore an object of this invention to propose a process for the production of carbon black with greater recovery efficiency and improved rate of production.
It is further object of this invention to propose a process for the production of carbon black by whic a more uniform quality of the product is obtained.
Another object of this invention is to propose a process for the production of carbon black which gives a wide variety of carbon blacks to meet desired specifications.
Yet another object of this invention is to propose a process for the production of carbon black which makes use of waste heat in the effluents and the combustion heat in the waste gases for better conservation of energy.
Other objects and advantages of this invention will be apparent from the ensuing description when read in conjunction with the accompanying drawings.
DETAILED DESCRIPTION OF THE INVENTION
Thus according to this invention is provided a process for the production of carbon black comprising burning a fuel with preheated air in a reactor to obtain an off-gas containing carbon black particles, hot gases and steam, quenching the reaction with a cooling fluid to obtain an effluent, subjecting the effluent to a step of cooling by
allowing the additional heat of smoke to dissipate into the atmosphere followed by a step of further temperature reduction by spraying with a second cooling fluid, and purification of the smoke,
collecting the carbon black from the smoke, subjecting the same to pulverisation, densification and drying to obtain carbon black.
In accordance wish this invention, a clean oil rich in aromatics, is preheated and injected axially into the reactors. Fuel gas or oil is burned with an excess of preheated air in a combustion section (this applies to hard black reactors only). The combustion gases enter the reactor choke section, forming a thermal cracking and combustion system with the oil spray and vapours. The combined heat from the hot gases and combustion of a portion of the feed oil by the excess air decomposes the remaining oil to carbon and hydrogen. The production of carbon black is
accomplished by the combustion and thermal decomposition of a hydrocarbon oil in a reducing atmosphere. This section of the process is characterised by its high temperature (1100 to 1650°C), low pressure ( 1 to 3 psig) and a relatively short reaction time (micro-seconds). The temperature, concentration of active ingredients and time to reaction in the carbon forming zones are controlled to produce carbon black having definite properties and the highest possible yields. In most cases, if the desired good quality and high yields of the carbon black are not accomplished in the first step of combustion, it cannot then be effected in the subsequent steps of the process.
[The decomposition of conversion oil to carbon black takes place in the heart of the
furnace, the reactor, and the type of reactor used will determine in general what
particle size carbon black will be obtained] A long reaction time at relatively low
temperature results in the formation of a large particle size carbon black of the Fast
Extruding Furnace (FEF), General Purposes Furnace (GPF) or Semi-Reinforcing
Furnace (SRFl) type. Conversely, a short reaction time at a relatively high temperature
results in the formation of small particle size High Abrasion Furnace (HAF) or
Intermediate Super Abrasion Furnace (ISAF) type carbon black. The effluent from
the reactor it an aerosol consisting of colloidal carbon particles suspended in a mixture
of hot gases and steam. These hot gases and steam, termed off-gas, convey the
carbon black. This effluent is quenched to 980oCor less by the primary quench
sprays. Therefore, these sprays serve two functions - one to arrest the reaction and
the other to control the outlet temperature. The effluent is thereafter subjected to
cooling by heat exchange. The cooling of the effluent results from a first step of heat exchange with air whereby the air is preheated and a further step of heat exchange with the conversion oil.
manner to reduce the! products. The steps
[For the process for leat exchange, the effluent or off-gas conveys the carbon black through pipes of wiste heat exchangers. In order not to damage the piping of these exchangers, the effluent is quenched. The effluent or smoke is thereafter first cooled in a shell and tube exchanger in which, the air is preheated in the shell and the smoke is cooled in the tubes. The second exchanger is the conversion oil preheater. This waste heat exchanger is a continuous coil type with the conversion of oil in the coil and the smoke in the shell. Each reactor is equipped with its own air and oil heat exchanger for ease of operation and maintenance. They are designed in such a
The partially coolec cooled by dissipation further temperature smoke temperature
amount of fouling obtained from carbon black and corrosion of the heat exchange can be accomplished in a number of ways and preferably to keep the velocity of the smoke high enough to keep carbon black from settling out in the exchangers.
smoke obtained from the step of heat exchange is thereafter of the additional heat into the atmosphere, followed by a step of reduction by a secondary quenching with a water spray. The may be, such as 285°C, at this point Too high a temperature of,.
for example, 315°C may destroy the collection means and too low a temperature for
example, 175°C may
cause excessive corrosion, mudding and decrese the life of the
collection means by depositing salts on them which weaken the cloth. All the water used
for stopping the reaction and cooling comes from the porcess water systems. Simultaneously, with the step of secondary quenching, the smoke is allowed to change direction rapidly, which results in settling of the large particles of cabonaceous or inorganic grit This waste material is periodically removed from the secondary quench
means by flushing
with water and discharging into a waste disposal system.
The additional heat is dissipated into the atomsphere by allowing the smoke to flow from the heat exchangers inot a common pipe called the smoke header. The step of secondary quenching is achieved in a secondary quench tower. The secondary quench tower also serves another purpose in that it makes the smoke pass over a baffle plate and change direction rapidly thus knocking out large particles of carbonaceous or inorganic grit This material is removed from the conical base of the tower periodically by flushing this part of the tower with water and discharging it to the waste disposal system.
In the next step, the carbon black is collected from the cool smoke by filtration and the residual gases are burnt for down stream seperation of the carbon black from the
and stem is accomplished at moderate temperatures of about for
example 300°C and low pressures of about for example 381 mm water gauge.
The carbon black thus collected is then pulverised. Tests are conducted on the black after being pulverised to determine if appreciable quantities of grit are present Carbonaceous grit usually comes from poor burners or operating conditions in the reactors. In organic grit can result from spalling of faulty refractories. Magnetic grit
fluffy black thus
is caused by corrosion of steel. The source of grit should be determined and eliminated to insure production of specification product Thereafter, the black is pneumatically conveyed to a collection unit and the effluent gases are recycled The
separated still contains some amount of air and gases and has a very low bulk density. Therefore, it has to be further densified before it can be used commercially. Thus is achieved by Palletisation. The water/carbon black ratio used is
1 for most blacks. By mechanical action, wet pellets with a diameter
of 0.5-2.0 mm are formed Binding agent like molasses is used to influence pellet
hardness. The wet pellets are thereafter dried This is achieved by dryers heated
externally, which may also be supplemented by hot gases passing through the dryers, to
lead to carbon black.
The collection of the carbon black is accomplished in a large structure containing several hundred specially treated fibre glass filter bags termed a bag filter. This is the only collecting device, which removes essentially 100% of the carbon black from the
off gas. Smoke enters the hooper below the bag filter cell plate and flows into the bags
through the cell plate. The hopper is perfoming as a distribution duct at this point The
off-gas flows through the pores of the cloth and the black is retained inside the bags.
Since the off-gases contain combustible gases, no air should be allowed into the system
after the reactor to avoid fires or allowed into the systems after the reactor to avoid
fires or explosions in the filter. The clean off-gases from each compartment are collected in a large common duet Part of these gasee are flow the dryer combuation
furnace where they flow to the boiler the reactor, filter blowers.
are used as low cost fuel under the dryer. The remaining off-gases
for burning. The energy required to overcome pressure drop across
and off-gas piping to the furnace is supplied by the process air
The carbon black i s conveyed from the bag filter hopper to a pulveriser. The pulveriser acts as a guard against the passage of large particles of grit into the product
The black from the pulveriser is pneumatically conveyed by a blower to a cyclone. The cyclone opera es at a few inches of water pressure drop and can achieve an 80% to 90% collection efficiency. The carbon black passes through a rotary valve into the loose black surge bank. The effluent gases from the cyclone are recycled to the bag filter.
The fluffy black is denaified by pelletisation in a wet pelletiser. The carbon black is mixed with water in pan mixers. The pellets are then dried in a dryer.
The invention will now be explained in greater detail with the help of the accompanying
drawing and wherein:
Fig. 1 shows a flow diagram of the process comprising the steps of
A; combustion in a reactor at a temperature of 1100 to 1650 C:
B: step of quenching by spraying with water,
C: heat exchange in two steps
C1 heat exchange with air,
heat exchange with conversion oil;
D. dissipation of heat into the atmosphere; E. secondary quenching by spraying with water and purification of the smoke;
F. collection of carbon black by filtration wherefrom part of the clean off-gas (a) is
lead off to be used as fuel under the dryer and another part (b) is piped % a boiler for
burning. The carbon black (c) is pneumatically conveyed forward for pulverisali
H. collection of pulverised carbon black;
I : pelletisation;
J : drying.
The carbon black produced by the process described herein has
been tested for its properties. It has given exllent results
on trials at the laboratory of one of the promonent type manu-
turers in India. The results are provide hereinbelow.
The effect of Carbon Black structure of aged samples on Mechanical properties of
Tyre tread compound is as follows -
A process for the production of carbon black comprising burning a
fuel with preheated air in a reactor to obtain an off-gas containing carbon black particles, hot gases and steam, quenching the reaction with a cooling fluid to obtain an effluent, subjecting the effluent to a step of cooling by allowing the additional heat of smoke to dissipate into the atmosphere followed by a step of further temperature reduction by spraying with a second cooling fluid, and purification
of the smoke, collecting the carbon black from the smoke, subjecting the same to pulverisation, densification and drying to obtain the carbon black.
2. The process as claimed in claim 1 wherein said fuel comprises fuel
The process as claimed in claim 1 wherein said fuel is burnt with an
of preheated air.
The process as claimed in claim 1 wherein the fuel is burnt at a
temperature in the range of 1100 to 1650°C.
The process as claimed in claim 1 wherein the fuel is burnt in a low pressure atmosphere of 1 to 3 psig.
The process as claimed in claim 1 wherein the combustion reaction is quenched with water to obtain an effluent.
process as claimed in claim 1 wherein after the step of quenching,
the temperature of the effluent is for example 980°C or less.
by heat by a set
The process as claimed in claim 1 wherein said effluent is cooled
exchange comprising a first step of heat exchange followed ond step of heat exchange.
The process as claimed in claim 8 wherein said first step of heat exchange is exchange of heat with air.
cess as claimed in claim 8 wherein said second step of heat
exchange is exchange of heat with conversion oil.
cess as claimed in claim 1 wherein during the steps of heat
exchange, the smoke is passed at a high velocity.
The process as claimed in claim 1 wherein said step secondary
quenching is effected with a water spray.
13. The process as claimed in claim 1 wherein after the step of secondary quenching, the temperature of the effluent is for example 285°C.
14. The process as claimed in claim 1 wherein the step of purification of the smoke is effected by a rapid change of direction of the smoke.
15. The process as claimed in claim 1 wherein the step of collection of the carbon black is effected at a temperature of for example 300°C and a pressure of about 381 mm water gauge.
16. The process as claimed in claim 1 wherein for the step of densification, the carbon black is subjected to pelletisation.
17. The process as claimed in claim 16 wherein for the step of pelletisation, the carbon black is mixed with water in a ratio of water/carbon black being approximately 1:1.
18. The process as claimed in claim 1 wherein pellests of diameter 0.5 to 2.0 mm are obtained from the step of pelletisation.
19. The procss as claimed in claim 1 wherein a binding agent such as
molasses is used to harden the pellets.
20. The process as claimed in claim 1 wherein said pellets are dried by
21. The process as claimed in claim 1 wherein said pellets are dried by hot air.
22. A process for the purification of carbon black substantial as herein described and illustrated.
DATED THIS 20TH DAY OF JANUARY, 2000.
( G.S. DAVAR ) OF L.S.DAVAR & CO., APPLICANTS' ATTORNEY.
|Indian Patent Application Number||75/MUM/2000|
|PG Journal Number||09/2008|
|Date of Filing||21-Jan-2000|
|Name of Patentee||HI-TECH CARBON|
|Applicant Address||A UNIT OF INDIAN RAYON & INDUSTRIES LTD, JUNAGADH VERAVAL ROAD, P.O. VERAVAL 362 266|
|PCT International Classification Number||C09C 1/48|
|PCT International Application Number||N/A|
|PCT International Filing date|