WO2000020514A2

WO2000020514A2 - An improved process for the manufacture of carbon black by furnace process and an improved high volume high temperature (hvht) reactor for carrying out said method

Info

Publication number: WO2000020514A2
Application number: PCT/IN1999/000046
Authority: WO
Inventors: Rabishwar Roychowdhury; Brahmanada Mukhopadhyay
Original assignee: Phillips Carbon Black Ltd.
Priority date: 1998-09-25
Filing date: 1999-09-13
Publication date: 2000-04-13
Also published as: WO2000020514A3

Abstract

An improved process for manufacturing carbon black by furnace process in High Volume High Temperature (HVHT) reactor. The process comprises burning liquid hydrocarbons supporting feedstock between 1800 to 2000 °C, allowing the hot flue gas coming from combustion zone to reaction zone of the reactor, allowing the pyrolysed smoke from the reactor zone to cooling zone to reduce the temperature, allowing said smoke to enter a cooler to bring down the temperature in passing said cool gas through an evaporating zone where it is further cooled with water spray, allowing the sprayed water droplets to absorb heat to get evaporated and passing the water quenched smoke into an air preheater for utilizing it in said combustion chamber.

Description

AN IMPROVED PROCESS FOR THE MANUFACTURE OF CARBON BLACK BY FURNACE PROCESS AND AN IMPROVED HIGH VOLUME HIGH TEMPERATURE (HVHT) REACTOR FOR CARRYING OUT SAID METHOD

The present invention relates to a process for the manufacture of carbon black by furnace process in High Volume High Temperature (HVHT) reactor and also said HVHT reactor.

5 This invention, in general, relates to an apparatus and an improved method for producing carbon black and in particular to control the surface area, particle size distribution, as reflected by tinting strength and other

10 colloidal properties. Additionally, the new process substantially increases the productivity and yield.

HVHT reactor essentially consists of four zones e.g. :

¹5 (a) Combination zone (Head Section)

(b) Reaction zone (Throat Section)

(c) Cooling zone (Cooler Section)and

(d Evaporating zone (Breeching Section)

This invention suggests ( 1 ) an improved design of combustion zone, (2) reaction zone and (3) an arrangement for feedstock nozzle for High Volume High Temperature (HVHT) reactor.

It has been found that the geometry and design of throat section of the reaction zone of HVHT plays an important role for achieving the desired result i.e. the excellent quality and efficient yield of carbon black.

Carbon black is known to be finely divided high carbonaceous pigment which is produced by burning of gas or liquid hydrocarbon feedstock in a deficiency of air under carefully controlled conditions.

It is an industrial product and is used in polymer industries and mainly in rubber industries as reinforcing, colourant and diluting agents for polymer/rubber to improve mechano-chemical and rheological properties for processing of raw compound and improving services of the cured product like tyre, conveyor belts, plastics, paints and inks etc.

The classification of carbon black has tradionally been based on the method of its manufacture. There are three; basic known methods which are as follows:

( ¹ ) The Channel Process

(2) The Thermal Process

(3) The Furnace Process

At present, the furnace process is extensively used for the production of carbon black mainly due to two reasons e.g.

1 ) The much improved production of economics of this process as against cost and availability of the raw materials for other processes of carbon black manufacture.

2) The technical advantage of oil furnace black of carbon black is characterised by following properties. (A) Particle Size

(B) Surface Area

(C) Structure

.(D) Surface Activity and

5 (E) pH

Today the latest carbon black technology includes the production of carbon black in improvement furnace process. Depending on the particle size and use, carbon black is divided ig into two broad categories, namely:

i ) Tread ii) Carcass

Most of the manufacturers of the developed countries who are the world players in the 15 field of carbon black, have developed- High Volume High Temperature (HVHT) reactors either for carcass or for tread variety in their own way.

All of the leading manufacturers in the above field have developed the advanced technology but lal the known method of manufacturing carbon black have certain disadvantages through the common goal mostly lies in the economics and quality.

To mitigate the disadvantages of the prior art methods for manufacturing carbon black, the applicants have concentrated on high volume high temperature tread black reactor and therefore, the following description mainly refers to the tread reactor.

Also to remove some of the operational constraints or disadvantages of the existing HVHT reactor, the applicant has developed a new design of the constrict section in the combination zone of the said reactor and the nozzle arrangement.

It has been observed that some parameters like throughput (make oil flow rate) and quality like CTAB (Cetyl Tπmethyl Ammonium Bromide), DBP (Di-Butyl Phathalate) and tint are mostly dependent on the following factors in addition to the spray condition of the feedstock.

(a)! Geometry of the Throat (b) Maximum coverage of flow area of oil spray

(c) Spray nozzle and

(d) Number of sprays

Among the above-mentioned four factors, the coverage of the flow area of the oil spray ^and the geometry of the throat are vital for controlling the quality, the throughput, yield and improvement of the refractory life of the HVT reactor. To get maximum coverage of oil spray in the flow are vital for controlling the quality, the throughput, yield and improvement of the refractory life of the HVHT reactor. To get maximum coverage of oil spray in the flow area of the throat section, it was found by the applicant that the optimum number of oil sprays should be least six. An object of the present invention is to achieve the maximum coverage of the oil spray in the cross sectional area of the throat of HVHT reactor by the feedstock (conversion oil) into the flow of the hot combustion gas by introducing at least six numbers of sprays of the feedstock.

Another object of the present invention is to minimize the flame length required during the pyrolysis using at least six hydrocarbons sprays and by keeping the flame well within the reaction chamber.

A still further object of the present invention is to minimize the residence time or duration of the pyrolysing the feedstock in the reactor by using substantially all the hot gases produced in the combustion chamber and thereby eliminating any waste of the enthalpy.

One more object of the present invention is the improvement of the service life of the 0514

throat section refractory as well as that beyond the throat section.

Still one more object of the present invention is to provide a bi-fluid atomization nozzle with wide angle spray for the supporting feedstock to achieve the complete combustion in the combustion zone of the HVHT reactor.

Yet another object of the present invention is to accomplish ^• more efficiency in the operation of HVHT reactor.

The above aspects are implemented by:

(a) Increased Throughput (Production Rate)

(b) Increased Yield (i.e. efficiency) and

(c) Higher Tint alongwith the following characteristics:

I ) CTAB

II) Nitrogen Surface Area

III) Iodine Number 20514

IV) 24M4 DBP (i.e. Compressed DBP) v) DBP as shown the Performance Analysis

The according to the present invention there is provided an improved process for the manufacture of carbon black by furnace process in High Volume High Temperature (HVHT) reactor which comprises the following steps:

burning completely liquid hydrocarbons supporting feedstock in a combustion zone to attain flame temperature between ''ΘOO to 200°C by passing axial air of 0.5 to 0.9 kg/cm^a (g) to achieve the continuous heat input of 75- 88 BTU/SCFH;

allowing the hot flue gas coming out of combustion zone containing 8 to ¹0% of excess oxygen into a reaction chamber;

- allowing the hot flue gas to pass through the said reaction zone of said reactor and injecting conversion oil in said reaction zone for pyrolysis reaction to take place;

- allowing the pyrolysed smoke from the reaction zone to enter into a cooling zone for reducing the temperature suddenly by increasing the residence time to improve the colloidal property;

allowing said smoke to enter a cooler to bring down the temperature thereof to "" 200 + "O0°C;

- passing said cool gas through an evaporating zone where said gas being being further cooled with the help of water spray for lowering its temperature;

allowing the sprayed water droplets to absorb heat to get evaporated;

passing the water-quenched smoke into an air preheater to preheat the air to 700 to 900°C for utilizing in said combustion chamber. 0514

The present invention further provides an improved High Volume High Temperature (HVHT) reactor for carrying out the above method comprising a Combustion Zone, Reaction Zone, Cooling Zone and Evaporating Zone wherein improvement comrpises in said reaction zone having multiple planes by adopting atleast size nozzles located in one or different planes of said reactor for spraying the combustion oil feedstock, said combustion zone being provided with a constrict section to enhance the speed of ther air injected into said combustion zone to form a turbula t mixture with the supporting feedstock, said combustion zone being connected to said reaction zone and said reaction zone being coupled to said cooling zone which is further connected to said evaporation zone to have a complete air tight assembly*

The second generation reactors for the production of the carbon black are the HVHT which is basically an improved reactor for production of carbon black by furnace process. This invented arrangement causes much better and rapid distribution of the oil droplets in the gas stream and also efficiently cracks 5 all the feedstock oil under the same thermal condition.

According to one embodiment of the present invention, we have adopted 'circular choke' with at least six burners in a plane. In i_fj comparison with the geometry of ¹0" I.D. standard design choke with "0" circular choke, there is a 5% advantage of spray area coverage than previous shape. We have found that circular chokes gave longer refractory life than standard

15 shapes make oil throughput (other conditions remaining same) increased but there was a marginal drop in tinting strength.

According to another embodiment of the present invention, we have changed the choke design 20 to a regular POLYGON with provision for using at least six burners m a plane. According to a further embodiment of the present invention, the geometry of the newly designed throat being a 8-¹6 sided regular POLYGON havine one oil spray port located in alternate sides having minimum provisions for at least six nos . of ports in each plane.

According to a still further embodiment of the present invention, the brink lining with lap joints and coated with plasma in hot face for better stability and easy repairs/replacement .

The carbon black is produced in a reactor which comprises the following four different sections:

( ) Combustion zone (Head Section)

(2) Reaction zone (Cooler Section)

(3) Cooling zone (Coller Section)

(4) Evaporation zone (Breeching Section)

If any of these sections under performs, there will be a substantial loss in yield, productivity and will also lead to quality deficiency. These can be well judged by the volume/mass of production and also the quality. The quality should be such that it should consistently produce a narrow and uniform particle size distribution reflected by tint and other colloidal properties of the particular grade produced, which is tested in laboratory as per ASTM method.

Feedstock used in the process of the present invention is the liquid hydrocarbons of petroleum and of coal tar origin. The pyrolytic reaction is carried in high temperature resistant refractory lined reaction zone in the deficiency of air.

As mentioned earlier, the oil furnace process for producing carbon black is well known, in which liquid hydrocarbon or the raw material (feed or make oil) is injected in a continuous stream of hot gas produced by burning the gas or liquid hydrocarbon commonly known as Supporting Feedstock ( SFS ) m the combustion zone. This hot gas is controlled in such a way that it contains known amount of free oxygen. The basic purpose of this method is that the hot gas is to suply the required amoμnt of heat for pyrolysis of feed oil to get converted into carbon black and the reaction is endothermic in nature. Excess oxygen is maintained to save the refractory which partially burns the feed oil. The pyrolysis and partial burning of feed oil takes place in the reaction chamber.

The pyrolyzed hydrocarbon which gets converted into carbon black and gaseous products is quenched in the cooling zone of the reactor where reaction is stopped as per the requirement.

Carbon black and combustion gas stream pass through the vaporizing section, air preheater, oil preheater and enter the bag filter, where carbon black is separated from gases and sent for further processing for packing and transport.

After leaving the combustion zone (as soon as combustion is completed), the high temperature flue gas with controlled amount of oxygen content enter in the mixing and reaction zone where the area is characterised by high stress factor which increases towards the throat, created by varying cross section _Q and high turbulartce due to very high flow and velocity. These are the two main characteristics for getting the desired properties (like surface area, structure etc.) of carbon black during pyrolysis reaction. At the same time, it is 5 also required to achieve higher production rate and improved yield for lowering down the cost of production. Thus an optimisation is needed considering all the above factors.

The reaction zone follows the mixing zone. o The reaction zone design depends on the throughput and residence time required for complete carbon black formation. In the process of optimisation, it has been established that a convergent nozzle with throat of polygonal shape with an equivalent diameter of "0 inch will give the desired result, also maximising the yield by minimising the side reaction by producing a short flame of exothermic reaction and pyrolysing the same by endothermic reaction.

As soon as conversion oil droplet is released from the nozzle to the hot gas stream into a converging throat which is the reaction zone, it immediately absorbs energy from the surroundings to vaporise at the unbalanced conditions. Pyrolysis reaction starts followed by combustion reaction and also at the same time, it is being struck by high velocity gas stream with a particular stress factor. The primary structure of the carbon black depends on stress factor. Lower the cross-section higher the stress factor.

The important properties like particle size, structure, surface area, surface activity and rubber properties like tensile strength, modulus etc. all primarily achieved m the first three sections of the reactor i.e. combustion zone, reaction zone and cooling zone by adjusting the process parameters and the residence time.

After working in cylindrical and non-crylindrical reactor of earlier generation, it was felt that improvement in both quality and cost are required to survive in the competitive market. Extensive studies were made to improve upon the quality and yield with different combination of parameters.

In the conventional design of the reaction chamber spray guns are adopted in various planes ranging from two to five and at each plane, normally two or four guns are used. As the number of planes are more in the conversional reaction chamber, likelihood of failure of refractory is too often. We have, on the contrary, adopted six to twelve guns at those planes of the reaction chamber selectively to get the best result and also thereby avoiding the failure of the refractory as observed in the known reaction chambers. Moreover, we have adopted at least six numbers of spray guns at each plane which gave the optimum result as mentioned in the specification.

Ultimately, it was decided by us that the first three sections of the reactor need total change in the design to -

l) achieve total and efficient combustion of liquid hydrocarbon supporting feedstock in head zone or combustion zone.

li) better coverage of hot gas produced in the combustion or head zone by the feed oil in the reaction zone, and

m) increase in the refractory life of reaction and cooling zone. ιv ) flexibility and ease of operation.

Priority was given to the reaction zone. The design was changed and the performance was extensively studied. Although a substantial improvement was noticed but it was more in quality.

Further studies were performed by the applicant and it was found that combustion section needs a proper design to achieve visibility of hot 9^{as an}d nozzle tips of feed oil by total combustion of liquid hydrocarbon supporting feedstock before reaching the throat of the reactor.

Modification was also done in the cooling section at the same time, to increase the ease of operation, flexibility an refractory life and to adjust the residence time more effectively by utilising thermodynamic and aerodynamic characteristics of the high temperature gas stream. 514

After the changes in design for above three zones, a very positive improvement both m quality and yield has been achieved.

To overcome the limitations, we have developed the section called "Throat" with a design of regular polygon which is having provision of using at least six numbers of burners in a single plane. The provisions for three nos . of plane at proper distances (to obtain a required cross section, hence the velocity) are provided to attain the required residence time for different grades to achieve wide spectrum of properties.

Another important aspect for better outcome of supporting feedstock which continuously supply the required amount of heat to facilitate the pyrolysis is endothermic in nature. This pre-pyrolysis activity, exothermic in nature, takes place on continuous basis in the combustion zone. The existing high volume high temperature tread reactor has various limitations for producing different grades of carbon black with wide spectrum of properties efficiently. Extensive studies have been made from different angles. In the first step of action plan, following changes were incorporated.

" ) Changing of original SFS (Supporting Feedstock) nozzle.

2) Selection of feedstock injection nozzle of predetermined angle.

Though some improvements were noticed, but it was failed to achieve the target of quality and efficiency of the production of carbon black. Further studies were made in second step of action plan and the following conclusions were arrived:

It was felt necessary to change the design of the throat section (reaction zone), the combustion zone and SFS to improve upon -

(a) Particle size distribution (PSD) as reflected m higher tinting strength of carbon black produced at identical process conditions compared to HVHT reactor of existing design.

(b) The visibility of the feedstock nozzle for conversion oil spray is a necessity to get optimum output.

(c) To have proper control of thermodynamic process and to eliminate the refractory failure, the heat input and the higher flame temperature required for endothermic pyrolysis for higher conversion and productivity by efficient and complete burning of SFS (Supporting Liquid Hydrocarbon Feedstock) within the combustion zone.

With same refractory condition, it is also revealed from thermodynamic, enthalpy leading to higher yield and efficiency. 0514

^■(d) The coverage of the cross-sectional area of combustion gas flow through the throat of the reactor by oil spray to utilise effectively the total heat generated by combustion of liquid hydrocarbon feedstock for efficient conversion of make oil.

Disadvantages in 2nd Generation Rector:

¹) In combustion chamber, the flame is unstable.

2) The combustion chamber is invisible due to carry over of unburnt gas (oil vapour) conversion oil (Liquid Hydrocarbon). Nozzle tip position cannot be located.

3) The aerodynamic characteristics is such that the flame is extended upto reaction zone.

4) Incomplete combustion in the combustion zone leading heterogenity and PSD irregularities often resulting process inadequacy and loss of conversion efficiency resulting in loss of yield.

5) Unstable flame heating the refractory wall. Due to this, skin temperature in this zone remaining high, resulting in heat loss.

To overcome all the above limitations, a new combustion zone has been designed by us.

Redesign parts includes two major activities e.g. :

(A) Designing a suitable bi-fluid atomisation nozzle for supporting liquid hydrocarbon feedstock, so that it can produce convergent and stable flame.

(B) Combustion should be completed within the combustion chamber.

After studying various bi-fluid atomisation nozzle, it has been found by s that a nozzle .with wide angle of having value of 90 degree and preferably between "20 and "80 degree when put into a high velocity zone, the stress that generated by high velocity air, reduce the angle of spray effectively to produce a convergent short flame. This results efficient mixing of air and oil and at the same time, total combustion is achieved within the combustion zone.

0 The mathematical modelling has been done and it is found that velocity in the range of '^■ 00- ""50 m/sec and preferably "30 m/sec is required to generate the suitable stress factor to fulfil the above requirement.

5 Therefore air quantity C 3, 000+150 nm3/hr.) being heated upto 800-900 degree centigrade passed through (3ⁱ0+40) mm dia opening, the required velocity is achieved.

Keeping the above factors in mind, reactor o (HVHT) has been modified and fruitful results are achieved. The achievement are as under:

" ) Combustion reaction completed with the combustion chamber.

2) Combustion chamber is totally visible and nozzle tip conversion oil gun are easily positioned.

3) Short convergent flame produced.

4) Increase in conversion yield.

This invention is explained in detail with reference to the drawings accompanying the provisional specification wherein

Figure-¹ shows the cross section of the reaction chamber of the new reactor.

Fιgure-2 shows the combustion zone of the new reactor. Figure-3 shows the by-fluid atomization nozzle of the invention.

With reference to the drawings, hot gas is injected into the reactor through the hot gas inlet (10) which has wide mouth (22). The neck of the hot gas inlet is gradually reduced in its diameter as shown at (20) in Fig." forming a tapered end at (24). At least siz spray guns are positioned at different planes of the reaction chamber. -Fig." illustrates guns located at two planes (30,32) having comparatively wide diameter while another set of spray guns are located at the narrowest section of the reaction chamber, namely (34). Spray guns are arranged at different planes of the reaction chamber for better circulation of the hot gas inside the reactor (40).

With reference to Fig.2 gas inlet (50) is located at one end of the substantial cylinder combustion zone (45). The location of said inlet for liquid supporting feedstock is shown at (50) which is at right angle to the air inlet (52). As the mixture of liquid supporting feedstock and air gets through the combustion zone of the reactor it faces a rather wide neck (54) which is gradually narrowed down into a wider area (56) and ultimately into a still wider area (58) into the reaction zone (60). Finally, the mixture passes through the other end of the reaction zone (70) to enter into the reaction of the reactor as illustrated

Fig.3 illustrates a by-fluid atomization nozzle for the reactor. The said nozzle (70) is closed at one end (80) and is open at the other end (75) and is located at one end of the combustion zone which is away from the reaction chamber. Near to the closed end of the said nozzle, there is provided a plurality of holes along its periphery so that oil can be sprayed through said holes (90) along the periphery (95) into the combustion chamber at a much wider angle. IV will dipict the results obtained by using the newly designed throat of the reactor as compared to the existing one.

Calculation based on Make Oil (Conversion Oil)

I) Analysis after changing the design of the Reaction Chamber (Throat) Yield is calculated as % of carbon black of make oil input

Date Grade Air Rate Air Temp. Make Oil % Yield on % Yield on newly % Increase (NM³/HR) °C (kg/hr) existing designed throat in Yield design

1 9.6.97 N220 ¹¹750 775 3325 53.0 54.56 2.94

- C_*O_* 20.7.97 N220 2500 750 3700 53.0 54. 8 2.22

1 2.7.97 N234 125¹6 789 3502 5".0 5".8 ".56

4.7.97 N330 2000 800 4450 59.0 60.53 2.59

17.6.97 N330 ¹2000 788 4300 59.0 59.6" ¹.03

29.7.96 N375 ¹2000 779 3850 55.0 55.7 ".27

29.7.96 N326 12000 760 4650 59.0 60.5^ 2.56

OIL BMCI = ^ 2 ; SULPHUR CONTENT = '.95% : EFFECTIVE BMCI = ¹25

II) Analysis after changing the design for both Reaction Chamber (Throat) & Combustion Chamber

Yield is calculated as % of carbon black of make oil input

Date Grade Air^Rate Air Temp. Make Oil % Yield on % Yield on % Increase (NM /HR °C (kg/hr) newly newly designed designed throat

"3.8.98 N330 ¹2000 788 4250 60.53 64.4 6.39

¹3.8.98 N330 11500 790 4 00 60.53 64.5 6.55

16.8.98 N220 13000 785 3650 60.53 56.5 3.55

¹7.8.98 N220 13000 784 3675 54.56 56.5 3.55

Ill) Comparison between newly designed Reactor Throat & Combustion Chamber with existing standard design Reactor

Yield is calculated as % of carbon black of make oil input

Grade % Yield for existing % Yield for newly designed % Increase in standard design throat 4 combustion chamber Yield

N220 53.0 ^'56.5 6.6

N220 53.0 56.5 6.6

N330 59.0 64.4 9. "5 O o

N330 59.0 64.5 9.32

Thus it is established that PCBL designed Throat & Combustion Chamber gices better Yield Yield is calculated as % of carbon black of make oil input

Reactor results are as follows :-

Grade Reactor % Yield I₂ Number DBP Tint CTAB ^N _? ^SA

N220 Unιt-3 56.5 '27.5 "25.0 ⁱ 3.0 " "¹.0 ^{< 1}9.0

N330 -do- 64.4 83.0 "3.0 'OAO 8".0 82.0

TABLE-IV

Grade Average yield on Make oil %

Newly Designed Existing Increae Throat and Standard Over the Combustion Design Existing Chamber (%)

N220 54.2 53.0 2.26

N234 54.2 51.0 6.27

N326 6 . 59.0 4.9"

N330 6A9 59.0 4.9"

N339 58.6 55.0 6.54

N375 58.6 55.0 6.65

Remarks

It must be noted that the data (Table I, II and III) studied have been taken from actual production data and the trial run carried out on commercial reactor under identical conditions by gas analysis through Orsat analysis apparatus .

Table IV indicates the average yield obtained by actual physical measurement on prolonged commercial runs under identical conditions. The average yield as shown in Table-IV, though much higher than the old standard design high volume temperature tread reactor are in some cases less than the result obtained from Orsat analysis data which are only indicative.

Therefore, it is established that improvement is achieved by the newly designed combustion chamber and throat over the existing old standard designed throat.

Results and Discussions:

Productivity :

Throughput In similar operating conditions the throughput is increased by approx. ¹0(%) (N330) over original reactors.

Air Temp, 780 degree C (avg.) Ratio ¹ : 9 Conv.oil Rate 440 kg/hr. for POLYGON ( " 2- 16 sided) with at least 6 burners. But with existing reactor only 4000 kg/"hr. 'Quality CTAB Better control in polygon throat with at least six burners.

Tint (particle pore size distrubution) - do -

DBP (agglomerate size distribution - do

Refractor life- Improved.

The design and the performance of the Sections specially the Combustion and Reaction Zone are discussed next.

Carbon Black Primary Process Derived Process Properties Parameters Parameters

Iodine Number Air-_^Flow ¹. Fuel-Air (mg/g) (Nm /hr.) Ratio

Air Tempera2- Air-Conv^ il ture (°C) Ratio(Nm /kg) 4

'Carbon Black Primary Process Derived Process Properties Parameters Parameters

3.Cooling Air 3. Heat Input Flow (Nm /hr) (BTU/SCFH)

DBP Absorption 4. Supporting 4. Flame Tempera(ml/l00g) Feedstock ture (°CJ (Kg/hr. )

5. Conversion oil 5. K'-Oil Ratio (PPM)

6. Reactor 6. Air Velocity Pressure _ gauge (kgt/m )

7. Oil Pressure (Bar)

8. Cut Off Water Flow

9. Oil Temperature ((°C)

Fixed Parameter : . Reactor Volume

2. Conv. Oil Nozzle Type : ANGLE Press.

3. Quench Water Nozzle Type : ANGLE, Press

4. Conv. Oil Gum Position.

Yield = function (f) = f(Air Temperature f(Heat Input). f(Air Rate). f(Supporting f(Flame Temperature), f(Oil Rate- Feedstock Flow) Conv. Oil). f(Side Reaction), f(Area covered by oil droplet in the Chock Section). f(Residence time), f ⁽Fuel/Air Ratio⁾, _f (oxygen concern.₎, f⁽0ⁱl press.⁾ f<»ci of oil, f( eynolds Number_),

To maximise Yield

Thermal decomposition to be maximised subject to the minimisation of Oxidation reaction (Side Rreactions₎,

Again, the number of nucleation for formation of carbon black depends on the number of eddies formed. For this, a very high turbulent flow is required. At the same time, it is followed by prolysis reaction which is also followed by release of additional energy by combustion reaction with the desired short flame.

For all the above, the situation demand a design of convergent nozzle where, for a given set of upstream condition, the linear velocity in the throat reaches that of sound in the gas at that location i.e. at throat it should be sonic velocity.

The characteristics of carbon black product having desired properties are generally dependent on the following factors:

1) Turbulance during- pyrolysis.

2) Type of spray pattern.

3) Type of liquid hydrovarbon feedstock. 4 ) Temperature of flue gas. 5) Temperature of the flame during pyrolysis.

6) Type/Geometry of the flame during pyrolysis.

7) Time required to accelerate the diffusion rate of the reactant constituents. 8) Type of nozzle (throat) through which the high gas stream passes.

The stress factor depends on the -

) Velocity of gas 2) Velocity of oil droplets 3) Oil droplet size.

Thus in throat section Plant-Ill has got 70% lower cross-sectional area than Plane -I and hence, stress factor is higher in Plane-Ill. As per the requirement of structure level of carbon black, oil guns are shifted from Plane- I_fII and III. DBP value also may be controlled by shifting conversion oil spray position.

Claims

We claim :

1. A improved process for the manufacture of carbon black by furnace process in High

Volume High Temperature (HVHT) reactor which comprises the following steps: burning completely liquid hydro- carbons supporting feedstock in a combustion zone to attain flame temperature between 800 to 2000°C by passing axial air of 0.5 to 0.9

2 kg/cm (g) to achieve the continuous heat input of 75-88 BTU/SCHF;

allowing the hot flue gas coming out of combustion zone containing 8 to 10% of excess oxygen into a reaction chamber;

allowing the hot flue gas to pass through the said reaction zone of said reactor and injecting conversion oil in said reaction zone for pyrolysis reaction to take place;

allowing the pyrolysed smoke from the reaction zone to enter into a cooling zone for reducing the temperature suddenly by increasing the residence time to improve the colloidal property;

allowing said smoke to enter a cooler to bring down the temperature thereof to 1200+ 100°C.

passing said cool gas through an evaporating zone where said gas being further cooled with the help of water spray for lowering its temperature;

allowing the sprayed water droplets to absorb heat to get evaporated;

passing the water quenched smoke into an air preheater to preheat the air to 5 700 to 900°C for utilizing in said combustion chamber.

2. An improved process as claimed in claim ι wherein said conversion oil feedstock is selected from petroleum base raw material and o also from coal tar origin. 0/20514

3. An improved process as claimed in claim wherein ratio between air and liquid hydro carbon feedstock varies from ^r to 20: so as to have 1000 BTU per SCFH to 00 BTU/20 SCFH of air.

4. An improved process as claimed in any one of claims 1 to 3 wherein in said reaction chamber conversion oil is injected through 0 nozzles in the atomised form for the partial combustion and pyrolysis of conversion oil.

5. An improved process as claimed in any one of the preceeding claims wherein water is sprayed co-currently or counter-currently 5 or radially to the direction of the flow of sa d smoke.

6. An improved process as claimed in claim wherein water is injected into the cooler in atomized form.

o

7. An improved process as claimed in claim

6 wherein water is sprayed through multiple -nozzles located at same or different planes of said cooler.

8. An improved process as claimed in claim ι wherein in said evaporation zone quenching is done with water spray so that water droplets get evaporated quickly.

9. An improved process for the manufacture of carbon black by furnace process in HVHT reactor substantially as herein described.

¹0. An improved High Volume High Temperature (HVHT) reactor for carrying out the method as claimed in any of the preceeding claims and Evaporating Zone wherein improvement comprises in said reaction zone having multiple planes by adopting atleast six nozzles located in one or different planes of said reactor for spraying the combustion oil feedstock, said combustion zone being provided with a constrict section to enhance the speed of the ^ai^r injected into said combustion zone to form a turbulant mixture with the supporting feedstock, said combustion zone being connected to said reaction zone and said reaction zone being coupled to said cooling zone which is further connected to said evaporation zone to have a complete air tight assembly.

1 . An improved HVHT reactor as claimed in claim ¹0 wherein a sprayed gun assembly is adopted to spray the supporting feedstock, said spray gun assembly is fitted with a nozzle provided with perforations along its peripheral line and is housed in said combustion zone.

12. An improved HVHT reactor as claimed in claim 9 or ¹0 wherein said reaction zone is substantially funnel shaped at its end connected with said cooling zone.

13. An improved HVHT reactor as claimed in claim "¹ or 12 wherein said cylinderical cooler is connected to said evaporating zone having one or more breeching sections.

¹ . An improved HVHT reactor as claimed in claim 1 wherein the throat section is located in said reaction zone having a regular polygonal shape with 12 to 6 sides for spraying the conversion oil.

15. An improved HVHT reactor as claimed in claim 11 wherein said reaction zone is provided with at least six spray nozzles for the conversion of oil feedstock, said spray nozzles being located at one or more planes.

16. An improved HVHT reactor as claimed in claim 14 or 15 wherein said reaction zone is provided with spray nozzles located at three different planes and each of said planes having 3 to 18 nozzles.

17. An improved HVHT reaction as claimed in any one of claims 0 to 6 wherein in said cooler or evaporation zones water spray gun assembly are positioned either in regular or ⁱrregular distances from each other.

¹8. An ⁱmproved High Volume High Temperature ⁽HVHT⁾ reaction substantially as herein described and as illustrated in the drawings accompanying the Provisional _Specificat_ion.