FIELD OF THE INVENTION
[0001] The present invention relates to a two way feeding arrangement system to increase individual effect overall heat transfer coefficient of Kraft FFFF MEE.
BACKGROUND OF THE INVENTION
[0002] A Kraft Multiple effect evaporator is considered as heart of Soda Chemical recovery Process dept. and Soda Chemical Recovery process department is considered as the Heart of whole Mill, and Kraft multiple effect evaporators is very Vital, Capital intensive equipment of soda chemical recovery dept. A little ignorance in pulping process can be reflected in multiple effect evaporators as Scale and in turn low solids content in final product. Low solids is main cause of Low reduction efficiency and Low steam generation per Mt BLD fired in recovery boiler and plugging of flue gas passes (path), high draught, high chimney emissions. In a nut shell overall recovery performance becomes very low.
[0003] A Kraft process is nothing but the Producing wood pulp by using cooking chemical (white liquor) Supplied by Soda chemical recovery process in a close pressure vessel called digester. As a rule of thumb IMt unbleached pulp produced in turn produces 12-14 m3 of weak black liquor which is sent to evaporation section of soda chemical recovery department. Weak Black liquor so produced contains 52-55% organic matters and 45-48%) inorganic matter. Total solids in this weak black liquor vary 10-18%) depending upon the type of technology employed, remaining is the water. pH of this WBL is 12-14, Residual alkali is usually in the range of 5 to 12 gpl and TTA is 25-48 gpl and temperature 80-90 deg.
[0004] A typical Kraft pulping process is as follows: Batch Process Details:

Cooking sequence:
1) Chips loading & liquor charging :1.50hr
2) First stage steaming : 0.75 hr
3) First stage retention : 0.75 hr
4) Second stage steaming :1.00hr
5) Second stage retention : 0.75 hr
6) Blow : 0.25 hr
Total Cooking cycle : 5.00 hr
[0005] Some paper industries are employing latest technology like continuous digester where in one side is fed with wood chips / Baggase, cooking chemical and LP/MP steam and from exit side unbleached pulp along with spent liquor is blown off to a blow tank. After Screening and Unbleached pulp washing, Spent liquor (weak black liquor) is sent to Soda Chemical recovery process dept. In Soda Chemical Recovery process dept this weak black liquor is stored in WBL tanks to maintain inventory. From the WBL tanks it is fed to Multiefffect evaporators in mixed feed/ backward feed arrangement depending upon the technology employed. Almost every modern paper Mill is using backward feed with seven effect falling film technology to handle highly viscous black liquors in final stage and better steam economy. Even some paper mills are using addtional 1st effect as falling film Super concentrator by utilization MP steam having temperature 170-180 deg C ( after desuperheating) and pressure 9-10 bar along with Recovery boiler's ESP ash, make Na2S04 mixing in 1st effect /Ilnd effect / Illrd effect depending the feasibility and this ash mixing is also frequently termed as sweetening, albeit very common is Seven effect plant where in 1st effect( finishers) utilizing LP steam of temp 138-148 DegC and pressure 3-3.4 kg/cm2 (after desuperheat). Solids concentration from super concentration can be as high as 85%. So 15% still water content in to it. Such a high solids content in final product is really appreciated by every mill but at such a high solids content salts in the system tends to crystallize over heat transfer areas and Very difficult to remove especially dicarbonate (2 mole Na2C03 and 1 Mole Na2S04), Burkeite

(1 mole Na2C03 and 2 Mole Na2S04) and Calcium scale. This Scale tends to increase day by day if not washed out timely, Operator reinforces the steam flow to manage overall WBL throughput to MEE so that SBL(HBL) stock is maintained (fuel for recovery Boiler). But eventually one has to take foul condensate/Weak wash boil out of complete evaporator train, which means turn down of evaporator plus additional steam requirement for water boiling (dilution).
[0006] Therefore, there exist a need to provide a two way feeding arrangement system to increase individual effect overall heat transfer coefficient kraft FFFF MEE.
OBJECTS OF THE INVENTION
[0007] The principal object of the present invention is to overcome the disadvantages of the prior art.
[0008] An object of the present invention is to provide a two way feeding arrangement system to increase individual effect overall heat transfer coefficient kraft FFFF MEE.
[0009] Another object of the present invention is to provide a two way feeding arrangement system that improves overall heat transfer coefficient i.e. increases capacity of overall plant.
[0010] Yet another object of the present invention is to provide a two way feeding arrangement system that improves steam economy from 5.5 to 6 and more.
[0011] Still another object of the present invention is to provide a two way feeding arrangement system that performs smooth functioning of all pumps, reduced maintenance cost, like seal damaging, gland leakages and others.

[0012] Still another object of the present invention is to provide a two way feeding arrangement system , wherein the plant shut is reduced to 10%, where as earlier shut down of single finisher body (out of 3 or 4)and cleaning of it was for 6-7 days
[0013] The foregoing and other objects of the present invention will become readily apparent upon further review of the following detailed description of the preferred embodiment as illustrated in the accompanying drawings.
SUMMARY OF THE INVENTION
[0014] The present invention relates to a two way feeding arrangement system to increase individual effect overall heat transfer coefficient Kraft FFFF MEE with three to four bodies for Effect-1 and three bodies for Super concentrator if there is super concentrator in the system. There are two bodies for Effect-2 namely 2nd A and 2nd B.
[0015] According to an embodiment of the present invention, the system, wherein ESP ash and salt cake (Na2S04) mixing system from Recovery boiler to a particular WBL tank namely A (31). WBL from this tank is sent Recovery Boiler by pump (36) for ESP ash and Sodium sulphate mixing in particular tank (salt cake cum ash mixing tank)(37) with proper agitator and after mixing comes back to WBL tank A(31). After mixing salt and ESP ash liquor comes back to tank-A(31) by pump (38). From this tank's (31) Overflow WBL come to a tank-B(32) which is approximately 1-2 meter low in height to tank-A(31). All the WBL incoming (from pulp mills) to WBL tank-A must pass from at least 150 or higher mesh size screen or cylindrical mesh filter (30).
[0016] Pit pump WBL to be stored in different WBL tank if required to be pumped to tank-A only through the WBL filter of mesh Size 150 or higher mesh .WBL suction is taken from WBL tank-B at 40% level for WBL feed Pump (33)

to evaporator. Before feed to Multi Effect evaporator there is a cylindrical mesh filter (38) of size 150 at least or more. From WBL Mesh filter out there two branches from which WBL is taken out followed by two flow meters one for backward feed (72) which quite ubiquitous and another for Forward feed (71).
[0017] If super concentrators are there, one super concentrator always remains in wash mode with Weak black liquor. Weak black liquor (forward feed) from branch -B is fed to wash mode super concentrator (13/14/15) at pump suction by valves 42/43/44 and wash product of this particular super concentrator is taken out at 50% level (sump level) via one of three valve (46/47/48) of body or exclusive extraction pump with control valve which fed to 1st effect 's (IA/IB/IC/ID) (l/2/3/4)one body pump suction as shown in the drawing no.8 by valves (51/52/53/54). And same taken out from 50% level (sump level) of any body of finishers via valves (55/56/57/58) and fed to either 2nd A or 2nd B recirculation pump suction leg by either gravity via valves (59/60) or by exclusive pump with control valve in delivery. And from these wash liquor is fed to Illrd effect Liquor vapor separator (cum flash tank)(18) or flash tank as shown either by gravity and valves (67/68) or by exclusive extraction pump with level control valve in its delivery line, from this vapor separator (18) Wash liquor taken out from the top 30-40%) level depending upon design and fed to Next (successive) WBL flash tank at bottom and so on till the liquor is fed to last effect(ll) i.e Vllth effect pump suction. In short One super concentrator body (out of 3 or 4 bodies), one finisher body (out of 3 or 4 bodies) and one 2nd A or 2nd B always remains in wash mode. During the forward feed steam remains open in the all super concentrator (including wash mode concentrator), all finisher and vapor to 2nd and 2nd B in controlled fashion utilizing individual control valves. Hence one can see there is 100%) utilization of equipment capacity.
[0018] If any MEE does not have 2ndA and 2nd B then one of 2nd effect or Illrd effect always remains in wash mode keeping vapor valve intact, what change is

wash liquor which further fed to WBL flash tanks till it is fed to Vllth effect recirculation pump suction after flashing.
[0019] While the invention has been described and shown with particular reference to the preferred embodiment, it will be apparent that variations might be possible that would fall within the scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where :
Figure 1 illustrates a view of the components of the present system; Figure 2 illustrates the quick start circuit of the present system; Figure 3 illsurates the flow chart of the user Interfaces of Pi A; and Figure 4 illsurates the flow chart of the user Interfaces of Pi B
DETAILED DESCRIPTION OF THE INVENTION
[0021] The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore the present description should be seen as illustrative and not limiting. While the invention is susceptible to various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.

[0022] In any embodiment described herein, the open-ended terms "comprising," "comprises," and the like (which are synonymous with "including," "having"and "characterized by") may be replaced by the respective partially closed phrases "consisting essentially of," consists essentially of," and the like or the respective closed phrases "consisting of," "consists of, the like.
[0023] As used herein, the singular forms "a," "an," and "the" designate both the singular and the plural, unless expressly stated to designate the singular only.
[0024] The present invention relates to a two way feeding arrangement system to increase individual effect overall heat transfer coefficient kraft FFFF MEE with three to four bodies for Effect-1 and three bodies for Super concentrator if there is super concentrator in the system. There are two bodies for Effect-2 namely 2nd A and 2nd B.
[0025] If at such a high solids content Steam condensate, Secondary condensate and foul condensate sealing is not proper, there are high chances of vacuum fluctuation in the MEE system if precisely investigated overall heat transfer coefficient gets reduced. Most of the time designers fail or stake over this unknowingly due to which overall WBL throughput (WBL consumption) get reduced severely. To overcome this Designer provides extra heat transfer area per MT water evaporated; Extra heating area in turn demands extra wetting rate M3/M hr and which in turn additional power consumption and additional structural cost. For which designer charges extra premium to client and overall capital required for the equipment becomes high, it becomes no more win-win situation. So there become so many negotiations and so many sellers to client finally one wins who has lowest quotation. But sometime these low quotes come with poor quality and compromise in other parts which is not easy for client to judge. Some good designers take a total heating area of 71m2/Mt for water evaporation in a Seven effect. Other designer for safest side may takes up to 115 M2/Mt water evaporation capacities. Whoever designer might be, one always

have at least 25% margin in every calculations for gauranties. So designers are copying the others with little bit modification without analyzing closely the other factors and design. If condensate sealing is not proper then even 120M2/Mt area become less and there is so much stagnation (hammering) due vapor and condensate mixing and there will be so much noise in the plant, if one is closely watching or investigating it, will find that there is high overall heat transfer coefficient U for VI and Vllth effect. And as we move on towards finisher, individual effect overall heat coefficient decreases steeply which unimaginable, and this all is due to poor condensate sealing even though MEE is clean by hydro jetting. A multiple effect evaporates is a special type of the plant where up to Ilnd effect system remains under pressure and from Illrd on up to last effect system remains in the vacuum. In heat exchanger those are under pressure or whose condensate is under pressure, designer uses a steam trap or condensate control valve to maintain condensate sealing as Shown in the drawing -LA steam trap allows the condensate to move out but blocks the steam and vapor to out. Also be note down that there are most the chance of struck up steam trap in open or close position. If it happens heat transfer severely reduced provided the additional steam flow. So designers give a steam condensate flash tank where in steam condensate level is controlled by using a control valve in the output (condensate out from Flash tank) or calculated size orifice with its bypass valve. There is a level transmitter which gives the feedback to control valve to close or open depending upon the level feedback. Inventor has find out that most of the times impulse lines of this steam condensate flash tank empty which again make the process poor and in turn low overall heat transfer coefficient. Also note down that in the drawing -2 that condensate coming out from heat exchanger (evaporator finisher) is taped in steam condensate flash tank at 6-8 inch above the 100%) level taping (level transmitter upper impulse line). Which never giving sealing to steam, in this way steam short circuits and moves to Ilnd effect calendria, Illrd effect calendria and so on depending upon no steam condensate flash tanks connected in series ( because operator give a set value of 50% level of condensate to be controlled ) Fig-3. Inventor has proposed an innovative way to

seal all the condensate from 1st effect to last effect as Shown in drawing-4 in condensate flash tanks. To make this happen Inventor has proposed that Steam condensate coming out from 1st effect calendrias (heat exchangers/Finishers) is fed to bottom of steam condensate flash tank and taken out at 50% of tank level to be controlled (by control valve)as shown in the drawing -4 and in this output there is a control valve and this control valve's output is fed to next steam condensate flash tank-2 in series at the bottom and taken out at 50% of successive tank level and so on till the last steam condensate flash tank. Advantage of this system is that first there is proper sealing, second is there is proper residence time for the steam condensate flashing and third is there is no hammering (in turn lead to leakage in condensate lines) in the condensate lines, lastly but the most importantly there is much-2 improved overall heat transfer coefficient of the 1st effect especially and overall individual effects.
[0026] A good chemical engineer can easily tell about the performance of multi effect evaporators just by seeing the temperature of following streams.i.e Temperature of any type of condensate (primary, secondary, foul) should not be more than 55 Deg C. And final product (strong black Liquor) temperature should not be more than 90 deg C.
[0027] As Explained above that Ilnd effect remains under the pressure but there comes some condition when it goes under vacuum i.e. Live steam flow rate is reduced for plant requirement. Designer proposes a secondary condensate flash system in which secondary condensate taken out form second effect calendria and fed at the top (70% level) and taken out from the bottom of the tank and fed next successive secondary condensate flash tank at the top and so on till the last effect. To control 50% level in any flash secondary condensate flash tank designer provides a designed orifice along with a bypass valve in the outlet condensate line as shown in the drawing-5. This is one of biggest design mistake as per inventor as orifice are never full proof for condensate controlling so sometimes there is condensate level are high and some time it rush to next (successive) Secondary

condensate flash tank with high velocity and hammering (noise) due to liquid and vapor mixing as per manometer effect( flow of liquid from high pressure to low pressure). So in such condition steam trap would not be feasible. So to remove condensate from this effect onward inventor has explained as follows:
[0028] Secondary condensate from Ilnd effect calendria is taken out and fed to bottom of Secondary condensate flash tank (meant for Ilnd Effect) without any control mechanism and taken out from 50% of the tank level and fed to next (successive)Secondary condensate flash tank(meant for Illrd) bottom without any control valve just with proper pipe sizing. Illrd effect secondary condensate taken out and fed to its secondary condensate flash tank at a level just 1 feet below the 50% level as shown in drawing-6 and this pattern remains continue till the last effect secondary condensate flash tank. Same thing is done for foul condensate flash tank also as explained by inventor.
1. There is one ESP ash and salt cake (Na2S04) mixing system from Recovery boiler to a particular WBL tank namely A (31). WBL from this tank is sent Recovery Boiler by pump (36) for ESP ash and Sodium sulphate mixing in particular tank (salt cake cum ash mixing tank)(37) with proper agitator and after mixing comes back to WBL tank A(31). After mixing salt and ESP ash liquor comes back to tank-A(31) by pump (38).
2. From this tank's (31) Overflow WBL come to a tank-B(32) which is approximately 1-2 meter low in height to tank-A(31).
3. All the WBL incoming (from pulp mills) to WBL tank-A must pass from at least 150 or higher mesh size screen or cylindrical mesh filter (30).
4. Pit pump WBL to be stored in different WBL tank if required to be pumped to tank-A only through the WBL filter of mesh Size 150 or higher mesh .
5. WBL suction is taken from WBL tank-B at 40% level for WBL feed Pump (33) to evaporator.
6. Before feed to Multi Effect evaporator there is a cylindrical mesh filter (38) of size 150 at least or more.

7. From WBL Mesh filter out there two branches from which WBL is taken out followed by two flow meters one for backward feed (72) which quite ubiquitous and another for Forward feed (71).
8. Inventor Proposes a MEEs System where in there are three to four bodies for Effect-1 and three bodies for Super concentrator if there is super concentrator in the system.
9. There are two bodies for Effect-2 namely 2nd A and 2nd B.

10. If super concentrators are there, one super concentrator always remains in wash mode with Weak black liquor. Weak black liquor (forward feed) from branch -B is fed to wash mode super concentrator (13/14/15) at pump suction by valves 42/43/44 and wash product of this particular super concentrator is taken out at 50% level (sump level) via one of three valve (46/47/48) of body or exclusive extraction pump with control valve which fed to 1st effect 's (IA/IB/IC/ID) (l/2/3/4)one body pump suction as shown in the drawing no.8 by valves (51/52/53/54). And same taken out from 50% level (sump level) of any body of finishers via valves (55/56/57/58) and fed to either 2nd A or 2nd B recirculation pump suction leg by either gravity via valves (59/60) or by exclusive pump with control valve in delivery. And from these wash liquor is fed to Illrd effect Liquor vapor separator (cum flash tank)(18) or flash tank as shown either by gravity and valves (67/68) or by exclusive extraction pump with level control valve in its delivery line, from this vapor separator (18) Wash liquor taken out from the top 30-40%) level depending upon design and fed to Next (successive) WBL flash tank at bottom and so on till the liquor is fed to last effect(ll) i.e Vllth effect pump suction. In short One super concentrator body (out of 3 or 4 bodies), one finisher body (out of 3 or 4 bodies) and one 2nd A or 2nd B always remains in wash mode. During the forward feed steam remains open in the all super concentrator (including wash mode concentrator), all finisher and vapor to 2nd and 2nd B in controlled fashion utilizing individual control valves. Hence one can see there is 100%) utilization of equipment capacity.
11. If any MEE does not have 2ndA and 2nd B then one of 2nd effect or Illrd effect always remains in wash mode keeping vapor valve intact, what change is wash

liquor which further fed to WBL flash tanks till it is fed to Vllth effect recirculation pump suction after flashing.
12. WBL temperature is usually 85-90 degC. WBL from Branch -A after Cylindrical mesh filter is fed to a flash tank or liquor cum vapor separator (20) where in liquor temperature is nearly 90 DegC and this effect is 5th Effect in the same fashion fed at the bottom taken out of the top (desired level to be maintained) till Vllth effect (11) recirculation pump suction leg.
mg/Kg ma
DS 200 x
mg/Kg M
DS 1000 ax
mg/Kg ma
DS 200 x
8
g/1 to 12
g/KG ma
DS 150 x
cp 300
DegC 18
M
mg/L 30 ax
[0029] Before claiming inventor has proposed following designed parameter to be maintain in Kraft MEE WBL Conditioning:
l.Ca as CaO 2. Silica 3.A1
4.Residual Na20
5.Na2S04+Na2C03
6. Viscosity
7.Boiling point elevation
8.Fiber

1st
Effe
ct Iln
d
effe
ct Illr
d
Effe
ct IV
effe ct V
Effe
ct VI
effe ct VII
Effe ct
Retenti on time (min) 122 25 21 17 15 15 13
Wettin
g Degree
(M3/M.
Hr) 7 7 4 4 4 4 4

1. During the whole system, washing of super concentrator, finisher body with WBL, Steam remains opened in all super concentrator/ finishers and other vapor valves remains open and intact as in normal operation in control fashion using steam/vapor control valves as per desired such that part of MEE train running as forward feed and part of the MEE running as backward train .
2. All the WBL from the pulp mill or other source comes in to a WBL tank-A only through a cylindrical mesh filter (30) size-150 at least or more.
3. WBL from WBL tank-A (31)is supplied to Recovery boiler by pump(36) for ESP ash mixing and sodium sulphate mixing tank(37) , sodium sulphate is mixed in such amount which fulfills the sulphidity in final white liquor.
4. After mixing ESP ash and Sodium sulphate (Na2S04) WBL again comes back to WBL tank -A(31) by pump (38). Due to Low concentration of Na2S04 almost all the Na2S04 gets dissolved in WBL.
5. WBL form WBL Tank-A(31) over flow, comes to WBL tank-B(32) (shorter in height to WBL
tank-A )(31).

6. From WBL tank-B (31), a suction line at tank height 40% is fed to centrifugal pump suction (33).
7. From centrifugal Pump WBL is fed to a cylindrical mesh filter(34).
8. From WBL mesh filter WBL's two branch is taken out, Branch A for WBL feed to Flash cum vapor separator tank (vapor separator of 5th effect (cum flash tank)) in backward feed manner through flowmeter (72), Branch B for WBL feed to one of Super concentrator (A/B/C) through valves (42/43/44) if there any for wash mode, or to Finisher body 1A/1B/1C/ID (51/52/53/54)in forward feed manner via flowmeter(71) see drawing no.8 .
9. WBL of washing is taken out from super concentrator via valves(46/47/48) or finisher from at 50-90% level in body by valves (55/56/57)as per level transmitter instead of recirculation pumps delivery line which is quite normal from most the design provided by supplier of MEEs.
10. Product liquor is withdrawn from super concentrator body or finisher body at a certain level which is to be maintained in the super concentrator or finisher body sump, instead of from recirculation pump delivery line. In this way there is zero interruption to recirculation in any body.
11. Product (SBL)from super concentrator or finishers undergoes to flashing sequence till the last effect as shown in the drawing i.e 2nd effect flash tank then 3rd effect flash tank and so on till the VII effect flash tank
12. Wash WBL taken out from Finisher body 1A/1B/1C/ID is fed to 2A/2B/3rd
effect at the suction by valves (59/60) and taken out from the Vapor separator
body via valves (67/68) or by exclusive extraction pump with level control valve
in its delivery line instead of recirculation pump delivery line, and fed to Ilird
effect vapor separator(18) at the bottom (as a flash tank) and taken out of the top
at predefined height.
13. Wash liquor from Vapor separator (Ilird effect)(18) is taken out and fed to
IV(19) effect vapor separator bottom and taken out from at definite height and fed
to V effect vapor separator(20) bottom in the same fashion till the last effect (11).
In this way there is proper retention for flashing of WBL.

14. WBL from Branch -A is fed to V effect vapor separator cum flash tank (20) bottom and which get mixed with the liquor already prevailing in it and follows the same pattern as discussed above till the last effect see drawing no.8 and 9.
15. Primary condensate from individual super concentrator SC1/SC2/SC3) is taken out by condensate line (Drawing no.5: 4,5,6) to its individual pots (1,2,3) at bottom, taken out from middle by its level control valves (7,8,9) and fmishers(IA/IB/IC/ID) is taken out by condensate line (18,19,20,21) and fed to its individual flash pots (11,12,13,14) at bottom and taken out at middle of the individual flash pots by level control valves (15,16,17,18) as shown in the drawing no.5 and fed to PCFT-1 at the bottom and follows the same pattern i.e. fed at bottom to PCFT2(37) by line (32) taken out by line (33) to feed to PCFT3 38. PCFT3 (38) taken out from middle by line( 34) and fed to PCFT4 (39), taken out form middle and fed to bottom of PCFT5 by line (35), taken out from middle by line (36) fed to bottom of PCFT6 . PCFT6 condensate also taken out from middle and fed to primary condensate supply pump suction by line (42) as shown in the drawing-5.
16. Refer drawing no:6 Secondary condensate from the second effect (2nd A and 2nd B) taken out by lines (l,2)and fed to its individual flash tanks SCFT-1A and SCFT-1B(3,4) at bottom and taken out from middle by lines(10,ll)and fed to next successive flash tank SCFT-2(5) at the bottom by line(12) also be note down that Illrd effect condensate is taken out from effect by line (17) and fed to SCFT-2(5) below one feet from middle and again taken out from middle of SCFT-2 by line (13 )to feed SCFT-3(6) and IVth Effect condensate taken out by line (18) fed to SCFT3(6) below one feet from middle and taken out by line (14) to feed SCFT-4(7), Similarly condensate of SCFT4 (7)is taken out from middle by line(15) to fed to SCFT5 (8) and Vlth effect calendria condensate is fed below one feet from middle of SCFT5 by line(20). SCFT5 condensate is fed to SCFT6 by line (16) Vllth Effect calendria condensate is fed to SCFT6 by line (21) in same manner. Surface condenser Condenser Calendria condensate is fed to secondary condensate pump suctionby line 22 as shown in the drawing no.6. It is to be note down that extraction from the flash tank is taken out at such a level that secondary

condensate of individual effect pipe is dipped in the condensate that there is not vapor condensate mixing or short circuiting as shown in the drawing -6.
17. Same pattern follow for the foul condensate sealing which is quite normally extracted from Vlth, Vllth and Surface condenser calendria.
18. Utilization of Soft water spray of 30-35 deg C to desuperheat the Vapor temperature incoming to the surface condenser from last effect to increase the vacuum in overall system as shown in drawing-7.
19. Scope of provision to install Eight effect Kraft black liquor evaporation plant in which Medium pressure steam (temp 170-180 dec C and pressure 6.0 kg/cm2 to 10 kg/cm2) is used for first effect super concentrator.
[0030] Advantages
1. Improved Overall heat transfer coefficient means increased capacity of overall plant. Inventor claims at least 30% increased plant capacity.
2. 100 % utilization of plant capacity.
3. Improved Steam economy.
4. A plant of 250 TPH evaporation requires approx. 1000 MT/day hot water for washing of finisher and other bodies which directly save 182 MT/day steam, assuming earlier steam economy -5.5.
5. Improved steam economy from 5.5 to 6 means for same plant means (50-45.5) 109Mt/day steam saving.
6. No stagnation of condensate.
7. Smooth functioning of all pumps, reduced maint. cost, like seal damaging, gland leakages and others.
8. Substantial Reduced High pressure cost approximately 70% of the earlier.
9. Plant shut is reduced to 10%, where as earlier shut down of finisher and cleaning of it for 6-7 days

10. Maint. Labor cost for by passing and opening closing the bodies is reduced.
11. Substantial reduction in power consumption due increased plant capacity.

[0031] Although the field of the invention has been described herein with limited reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications.

Claim

1. A two way feeding arrangement system, comprising;
i. three to four bodies for Effect-1 and three bodies for Super concentrator, two bodies for Effect-2 namely 2nd A and 2nd B.
ii. WBL is sent Recovery Boiler by pump (36) for ESP ash and Sodium sulphate mixing in particular tank (salt cake cum ash mixing tank)(37) with proper agitator and after mixing comes back to WBL tank A(31).
iii. After mixing salt and ESP ash liquor comes back to tank-A(31) by pump (38).
iv. From this tank's (31) Overflow WBL come to a tank-B(32) which is approximately 1-2 meter low in height to tank-A(31).
v. All the WBL incoming (from pulp mills) to WBL tank-A must pass from at least 150 or higher mesh size screen or cylindrical mesh filter (30).
vi. Pit pump WBL to be stored in different WBL tank if required to be pumped to tank-A only through the WBL filter of mesh Size 150 or higher mesh .
vii. WBL suction is taken from WBL tank-B at 40% level for WBL feed Pump (33) to evaporator.
viii. Before feed to Multi Effect evaporator there is a cylindrical mesh filter (38) of size 150 at least or more.

ix. From WBL Mesh filter out there two branches from which WBL is taken out followed by two flow meters one for backward feed (72) which quite ubiquitous and another for Forward feed (71).
2. The system as claimed in Claim 1, wherein washing of super concentrator, finisher body with WBL, Steam remains opened in all super concentrator/ finishers and other vapor valves remains open and intact as in normal operation in control fashion using steam/vapor control valves.