Factory Engineering A REVIEW ASH HANDLING … Sawyer A Review of Ash... · A REVIEW OF ASH HANDLING...

Factory Engineering

A REVIEW OF ASH HANDLING SYSTEMS IN QUEENSLAND SUGAR MILLS

G.M. Sawyer and R.N. Cullen I Sugar Research Institute, Mackay, Queensland, Australia

I ABSTRACT 1

This paper reviews the variety of ash handling plants which have been employed with the modern large suspension fired boilers used in the Queensland sugar industry. Reference is made to the investi- gational work carried out by Sugar Researoh Institute, Mackay in this field. The chemistry of bagasse fired boiler ash is discussed, and the individual nature of each installation is emphasised.

INTRODUCTION

During the last seven years the quantity of fly ash collected from bagasse fired boilers in the Queensland sugar industry has increased dramat- ically. This has been due to the increase in boiler capacity and to the fitting of high efficiency dust collectors to all units. Both of these factors have been influenced by the Clean Air Act which was introduced in 1970 and with which all boilers must comply by the 1977 season.

In a seven year period the average size of boilers in the industry has increased from 18 700 kg steam/h to 68 000 kg/h an increase of 360%. Total installed steaming capacity has risen by 61% over the same period. This has been due to larger units replacing sillaller units which were un- economical to convert to meet Clean Air Standards. The largest boiler so far commissioned has a steaming capacity of 180 000 kg/h and a unit of 200 000 kg/h capacity will be installed for the 1977 season. To comply with the Clean Air Act emission standards of 0.69 gm/std m3 either dry collectors of 90-92% efficiency or wet scrubbers of 97-99% efficiency, depending on specific application, have been installed on all boilers. It is estimated that for the 1977 season the total quantity of wet ash that will need to be handled from Queensland nlills will exceed one million tonnes.

The great incrqase in ash quantities has posed many problems to sugar industry engineersiVwet sluicing of ash is part of a scrubber system and it

i has been used extensively in conjunction with dry collectors to transport collected material to a convenient area. A closed loop recirculation system for the sluicing water is the only realistic solution if water pollution problems, due to discharge of ash laden water, is to be avoided. The effective operation of a closed loop system depends heavily on the effectiveness of the settling systems and considerable development on these have taken placeCin recent years.

2263

2264 FACTORY ENGINEERING

This paper reviews some of the ash handling systems that have been successfully developed. In particular reference is made to some of the pilot plant development work on ash settling and dewatering that has been carried out and which formed the,basisLfor some of the new installation designs. The fact that no 'universal' system has been developed emphasises the fact that systems must be individually tailored in each application depending on such aspects as collector type and location of the plant.

THE CHEMISTRY OF FLY ASH

An example of the size distributio~~ of fly ash from bagasse suspension fired boilers within the Queensland sugar industry has been given by Cullen and Ivinl. They indicate that the size distribution can vary between 1 and 500 microns, with 20% to 30% being sub-lo micron. This size distribution is confirmed by figures from Flood, Honey and Munro2.

An analysis of a sample of the material from a particular Queensland mill in the central region reveals the following:

Fine and fly ash, specific gravity = 2 .14

% combustibles (i.e. finely divided carbon) = 33 .O%

and % incombustibles = 67.0%

Of the incombustibles approximately 67.0% was silica as Si 0, and 23% was aluminium as A12 0).

% inoisture (wet basis) at saturation = 62.0%

The material is thixotropic. Coarse ash which constitutes only about 20% of the total ash collected

from a suspension fired bagasse boiler consists predominantly of a mixture of larger fused particles of the incombustible substances and partially com- busted bagasse. Invariably the partially burnt material will float, while the incombustible substances will settle fairly quickly by comparison with.the finer fly ash material because of their reduced wetted-area per unit volume of particle.

Most modern ash handling installatioi~s dispose of grate ash by an independent submerged belt system or a grate hopper sluice into a common ash slurry tank for later dewatering by settling out with the fly ash in a single settling device. The design of suitable sluicing equipment for handling this material seems to offer few problems. The major efforts in ash handling have been directed towards the removal of fly ash from the recirculated sluicing water.

SUBMERGED BELT SYSTEM

The first of the new generation of large suspension fired boilers to be installed [Jacklin and Arrowsmith 197031 was fitted with a submerged belt ash handling system. This system collects ash discharged from the grate

G.M. SAWYER AND R.N. CULLEN

2265 I and from the hoppers of the dust collector (approximately 80% efficiency) and from the spray chambers. This system initially suffered from floaters which prevented the submergellce of solid ash thus inhibiting delivery .of ash to the belt. This situation was overcome by fitting powered rakes moving through the water to provide positive discharge to the belt. Dredger blades were installed on the first section of the belt to give positive continuous movement of both solid and floater material. These also allowed i drainage.

This system has been included in several subsequent installations, all using multicyclone collectors, and further modifications have included the use of screens to remove unburnt floaters before they get to the submerged belt section. This unburnt material can be discharged directly to the belt. I 1 The settling area in the submerged belt section has also been increased to improve settling of the smaller particles removed when collector efficiency is increased from 80 to 90%. The material discharged to the ash hopper is however still quite moist and drains freely. Spears have been incorporated in the hopper to remove excess moisture.

Submerged belt systems have the inherent quality of poor hydraulic conditions for settling. Although it is possible to provide a submerged belt of sufficient length to provide a loading ol 50 to 100 (l/min)/m2, they are usually provided with limited take-off launders at one end such that the settling zone can be likened to a channel in which velocities are high and settling poor. The shallow depth of the submerged belt system does not provide for a distinct settling zone and ash zone as in other devices and so re-entrainment of fines is extremely likely.

THE 'CONVENTIONAL' SETTLING TANK

The first ash settlers of this type were installed in conjunction with wet scrubbers in 1970 in a Mackay factory and based on a design figure of 21.8 l/min of influent/m2 of settling area, which had been established after limited pilot plant testing. These settling tanks operated successfully over several years and were known to be conservatively rated. To obtain more comprehensive data on settling capacities, a pilot plant was constructed by Sugar Research Institute incorporating a tank with a settling area of 0.75 m2.

The pilot plant is illustrated in Fig. 1. The construction of the settling tank was similar to that used on the full sized units with a transverse feedwell on the back waII, transverse take off launder on the baffle wall, a 4S0 discharge incline, negligible dewatering zone and full width scraper conveyor for underflow removal. The authors concluded from the tests conducted that a maximum loading of 50 (l/min)/mt should not be exceeded in designing such a settling device. This figure allowed for an overflow concentration of 0.5% solids for an inflow % solids of 4.0% (i.e. overflow % solids = 0.125 inflow % solids). At that time a 4.0% concentration of ash in waier was considered the maximum permissible to ensure that the slurry pump performed satisfactorily.


Variable s ~ e c d

Pump

scraper conveyor

FIGURE 1 . Conventional settling tank - pilot plant.

It was also noted that the performance of the settling tank was signif- icantly affected by scraper conveyor speed. A reduction in speed from 0 . 8 to 0 . 4 m/min resulted in an increase in obtainable loading from 5 0 . 0 to 73 .5 (l/min)/m2. Obviously a fast speed will stir up the settled ash and encourage re-entrainment in the outflow while too slow a speed may result in insufficient scraper conveyor capacity.

Other points of note were:

a) The wetness of the discharged underflow was dependent upon dewatering time, so that increasing the dewatering time allowed for additional drainage of the ash and produced a dryer ash on discharge.

b) The discharged ash possessed considerable shear strength as it piled up with almost vertical sides.

FIGURE 2 . Ash handling system incorporating J.T.A. conventional settling tanks. --

n Dry belt conveyor . - - n n

~ v c r f l o w ~ c u l a t i o n pump ~

G.M. SAWYER AND R.N. CULLEN

John Thompson Australia Pty. Ltd., has developed the conventional settling tank over the past lew years, encompassing several installations, into a reliable piece of plant requiring minimal maintenance and surveillance. The most recent John Thompson installation is depicted in Fig. 2.

The boiler station that this system serves consists of three boilers, a new John Thompson 1 13 000 kg/h boiler and two Babcock and Wilcox 64 000 kg/h boilers. The larger boiler is fitted with a CSR wet fly ash collector, a mud drum grit sluice and submerged belt for grate ash disposal. The two smaller boilers are fitted with dry fly ash collectors and auxiliary wet scrubbers, mud drum sluice and submerged belt grate ash disposal.

The grate ash of all three boilers is handled separately by a single submerged belt onto which all grate ashes are periodically dumped. The grate ash is discharged from the submerged belt onto a dry inclined belt conveyor for transport to the ash/mud bunker. This conveyor also receives the underflow ash dragged from the settling tanks and also all mill mud.

The separate fly ash and mud drum grit handling system incorporates two settling tanks to remove the ash collected by the recirculating water which is pumped around at a design rate of 4 500 l/min. The sluicing water is passed through the wet collectors, dry collector launders and mud drum launders by means of several pumps and distribution boxes. The 'dirty' water is finally divided and passed to four ash screens. The screens are 1 . 0 mm DSM type with two per settling tank. Each is 1 575 mm wide and discharge at an angle of approximately 45O. An additional section of flat screen approximately 460 mm long has been attached tangentially to the bottom of each screen. This allows greater removal of moisture from the screen overflow of large ash particles, floater and unburnt bagasse. This material is discharged onto the dewatering section of the dragouts of the settling tanks.

The underflow from the screens is piped to the central longitudinal feed well of each settling tank. The underflows from the additional sections of screen are collected and directed into the settling zones of the tanks. The settling zone of each tank is approximately 9.5 m long x 3.2 m wide and the central feedwell is .46 n~ wide. Two longitudinal overflow launders in each tank accept the overflow and carry it to a collection bin at the back end of each tank to which makeup water is added for recirculating to the ash collection equipment.

The settled ash is drawn from the tank by means of a 1 .25 m wide slat conveyor operating at 0 . 8 m/min which carries the ash up the 30° inclined sections at the front of each tank. The ash is dewatered for a period of approximately five minutes before being discharged onto the dry belt conveyor.

The settling tank loading based ,on the gross settling area and design pumping rate is 74 (l/min)/mz for/ which!an average inflow of 0 .23% solids was reduced to 0 .07% solidsi\in oierflow (i.e. overflow % solids = 0 . 3 x inflow % solids). The ash discharged onto the dry belt conveyor


varied between 3 1 % and 83 % moisture, which is very wet. Even so when it is combined with mill mud it apparently presents no problems in bun- kering or on later transportation. By comparison ash of similar moisture when bunkered alone has been difficult to remove from the bunker, and the high moisture content and thixatropic nature has resulted in considerable spillage of material from motor trucks during transportation from the factory.

The major problem associated with conventional settling tanks has been in handling the wet discharge material. A number of devices such as spears and narrow vertical strips of screen down the sides of the hopper have been fitted to ash bunkers to promote draining of the material. Moderate to reasonable success has been reported, but in general the short residence time of the ash in the bunker m::iis that the material is still quite wet when loaded into motor trucks. Hanging up of the material in bunkers when emptied has resulted in a significant red.lction in the live capacity of ash bunkers. The combination of wet ash : 1 dry filter mud seems to offer the best solution to all three problems of ash wetness, caking in bunkers and transportation. $,. #

THE ASH SUBSIDER AND FILTER

The trials on the settling capacity of a pilot conventional settling tank were extended to a pilot ash subsider. The pilot subsider which had a settling area of 0 . 9 m2 and a capacity of 1 300 litres was the same plant used by Hale and Whayman4 in their studies on the settling of mud.

A continuous loading of 75 (l/min)/m2 was achieved for an inflow % solids of 2 . 8 % and an overflow % solids of 0 .4% (overflow % solids = 0.14 x inflow % solids). The underflow discharge rate was varied periodically in order to maintain a constant head of settled ash, and averaged 0.155 times the feed rate. The average % solids in the underflow was 12.3 % (i.e. 87.7% moisture). The underflow was a slurry, even though on occasions its moisture content was as low as 85.5% because of the thixotropic nature of the material. A second stage of underflow dewatering was obviously necessary with the ash subsider to produce an ash which could be bunkered.

A 900 mm diameter horizontal rotary vacuum pan filter was installed alongside the pilot subsider to evaluate filtration of underflow ash on a continuous basis. The pilot filter proved the feasibility of rapidly dewatering the ash under low vacuum to produce a cake of moisture content less than saturation. The details of these trials have been reported by Sawyer and Cullen5 and indicated a filter design rating of 50 (l/min)/mz. Subsequent filter leaf tests by a filter manufacturer indicated that the design rating could be increased to 90 (l/min)mZ for a horizontal vacuum filter belt suitable for ash dewatering and to satisfy the following criteria:

Feed - - 14.0% solids Final ash - - 60.0% moisture Saturation - - 62.0% moisture Vacuum - - 150 mm Hg Air flow rate - - 26.2 ( l/min) /m2

G.M. SAWYER AND R.N. CULLEN 2269

As reported by McDougall, Messiter and Sawyela the Racecourse ash handling system was designed on the data obtained from the pilot trials and incorporated :

a) CSR wetted louvre flue gas scrubbers

b) Recirculating water system

c) S.R.I. subsider

d ) A horizontal vacuum filter belt

The total ash handling system is depicted in Fig. 3 and during the 1975 season handled the ash from the newly commissioned 150 000 kg/h boiler. In this system all ash is sluiced to a common trough from which it is pumped over bar screens to remove floater before entering the ash subsider. The 'clean' overflow from the subsider is returned to the arrestor and the ash laden underflow is discharged onto the horizontal vacuum filter belt below for dewatering. The 'dry' ash cake issuing from the filter belt drops into the ash bunker. The subsider, filter belt and ash bunker are supported by a single staging which is sufficiently high to allow the ash bunker to discharge directly into motor transport.

FIGURE 3 . Racecourse mill ash handling plant.

Hydraulic Stlrrer Orlve

The subsider was designed for a recirculating water rate of 7 440 kg/min. A cross sectional area of 8 9 . 4 m2 was selected (10 .7 m2 diameter) giving a design loading of 83 . 4 ( 1 /min) /m2. Subsequent tests indicated that the loading could be increased to 100 (l/min)/m2.

The pilot plant studies indicated that the high shear strengths of the concentrated settled ash imposed severe torque loads on the stirrer drive. It was considered that a steep cone would assist in reducing stirrer torque


requirements by encouraging the ash to move under the effect of gravity. The stirrer was not able to be eliminated as the pilot plant indicated it was necessary to encourage continuous movement of the settled ash towards the outlet to prevent bridging. A robust hydraulically driven stirrer was thus provided which is capable of delivering 76 000 N-m torque at the centre shaft.

The horizontal vacuum filter was sized by the manufacturer and included a liberal design margin. The size selected was 1 .22 m wide x 4.27 m long.

The performance of the ash subsider was considered to be exception- ally good with the average overflow solids being 0.14% for an inflow solids of 0 .6%. The underflow a$efaged 81.0% moisture higher than anticipated. Underflow discharge through a 'Clarkson' type (constant cross section, variable orifice) valve proved effectiv.e, although scouring of the rubber liner was to be expected.

Performance of the vacuum filter in terms of dewatering was better than expected with the final cake containing only 50% moisture. However considerable problems were experienced with the filter cloths which abraded badly at the stitching and tracked poorly.

More recent proposals for similar ash handling systems on two boiler installations of 200 000 kg/h and 113 000 kg/h steam capacity yet to be commissioned, specify a top-feed rotary drum filter in place of a horizontal vacuum filter as used at Racecourse. As the filter media is firmly attached to the rotary drum it is anticipated that they will prove a better alternative to the filter belt.

HYDRAULIC CYCLONES AND BAR SCREEN

One northern Queensland mill has installed the ash handling plant depicted in Fig. 4 on a boiler of 63 600 kg/h capacity fitted with dry arrestors. The ashes are removed from the boiler through sluices which run into a common tank and are pumped to the ash handling plant through 150 mm polyethylene pipes. The ash slurry is first passed over a'n 800 mm wide, 3 mm x 50° bar screen, the underflow of which is collected and delivered by pump to two 300 mm diameter hydraulic cyclones. The return from the hydraulic cyclones is collected and recirculated to the boiler sluices. The discharge from the hydraulic cyclones and bar screen fall into a mud screw conveyor which delivers the mixture into a bunker. To ensure a desirable consistency of mud/ash from the bunker, a bleed pipe is provided from the hydraulic cyclone return line Lo the screw conveyor to allow additional moisture to be added to the mixture as desired. It should be noted that the mud in this installation is very dry and it comes from a mud cyclone.

G.M. SAWYER AND R.N. CULLEN 227 1

FIGURE 4 . Ash handling system incorporating hydraulic cyclones. CollectIan tank

Inflow from

Floater material Kscrw Cyclone overflow

rwnlfile d~scharge Bar screen underflow

Recirculating pump \\ - filter mud conveyor \'

To boiler sluices

Milford 19767 has reported typical inflow concentrations to the bar screen of 6 . 0 % solids and recirculated water concentrations of approximately 5 .O% solids. Limited tests by Sugar Research late in the 1976 season indicated inflow concentrations to the screen of the order of 13 .5% solids and concentration of the recirculated water of approximately 12.6% solids. The discharge from the screen was very wet and in the range 13. to 23% solids. The screen underflow which is delivered to the inlet of the hydraulic cyclone was approximately 12.9% solids. The discharge from the hydraulic cyclones was a soupy slurry of approximately 59.0% solids. It is obvious that in this system recirculation concentrations are high. Even with these high levels of conceiltration factory engineers have reported that the system has proved stable under most conditions. The high solids content of the recirculating water however has resulted in considerable wear on the bar screen.

A similar system incorporating three hydraulic cyclones of varying sizes (300 mm, 200 mm and 150 mm) and one bar screen has been employed at a second factory in the same district. To date however the system has proved incapable of handling the ash produced by the 180 000 kg/h boiler. Severe erosion has resulted in the hydraulic cyclones suffering dramatic deterioration in performance after only one week of operation.

THE MOURILYAN MILL ASH REMOVAL SYSTEM

Logan8 has reported the installation of a novel ash handling plant at Mourilyan mill which is designed to eliminate the wear associated with the scraper conveyor system and which is claimed to give trouble free performance. The installation is illustrated in Fig. 5. It is essentially a modified conventional settling tank in which a 6 m diameter paddle wheel is used to remove the settled ash from the b0tto.m- of a semi-cylindrical concrete lined settling tank. 1, ;;;, ~


pile

concrete

settlmns tank

FIGURE 5 . Mourilyan mill ash removal system.

The paddle wheel has 2 440 mm wide paddles arranged on the periph- eri of the wheel at a spacing of 610 mm. The wheel rotates at a peripheral speed of 1 . 8 m/min and rakes the settled ash from the tank. The ash is deposited o~i to a 610 mm wide rubber belt which delivers it to the ash pile. Ash is removed daily by a front end loader and motor truck.

Water lost from the system is replaced by means of a f1,oat switch located in the settling tank while water which drains from the ash pile is also directed back into the settling tank. The 'clean' recirculating water overflows from the discharge end of the tank and is pumped back to the boiler for sluicing at a controlled rate of approximately 1 900 l/min.

The ash removal system has been recently connected to the newly commissioned 159 000 kg/ steam/h boiler fitted with high efficiency collectors and mill engineers report that no apparent build up of ash concentrations have occurred at an average steam rate of 127 000 kg/h and maximum bagasse usage rate. From their obse,i..yations, the ash is apparently predominantly silica and contains only a m a l l quantity of unburnt material.

Quantitative data on the settling performance of the system is not available.

DRY ASH REMOVAL SYSTEMS

Where dry ash collection apparatus is lilted to a boiler it is possible to remove dust without sluicing. Several dry type removal systems are installed in Queensland mills. One mill has a dry system for the removal of the fly ash installed on a recently commissioned 180 000 kg steam/h Babcock and Wilcox boiler. The system designed and installed by the boiler manufacturer is illustrated schematically in Fig. 6.


FIGURE 6 . Ash handling system incorporating dry fly ash removal and coarse-ash sluicing.

Ash bunker n \ Fly ash collectors

I I I I

Screw conveyor I Rotary valve -

Mixing conveyor I_ 1

Water drum ash hopper r I

, Stoker ash happers

I I ----- I

Submerged belt conveyor I u - 1

Grate ash hoppers

The fly ash which collects in the steep rectangular sectioned hoppers beneath the dust collectors is removed by a screw conveyor which discharges the fine ash through a rotary valve into a mixing conveyor to which water is added and thoroughly mixed with the ash. The dampened ash is then discharged onto a troughed conveyor belt for transfer to the ash hopper. The quantity of water added is manually controlled and is continuously maintained visually by means of a T.V. camera mounted over the troughed conveyor and a V.D.U. in the boiler control room.

The coarser ashes are removed separately by a combination of submerged belt for the grate ash and sluicing of the water drum hopper and stoker fire ash hoppers. The recirculated water is drawn from the downstream end of the submerged conveyor which discharges all of the settled coarse ashes onto the dry troughed conveyor belt.

The system eliminates the problen~s associated with settling of the very fine fly ash material, and at the same time is quite compact in comparison to wet systems. Few problems have been experienced with the plant since it was commissioned and the majority of these have been as a result of an over capacity sluice pump.

ASH PONDS

The preceding ash handling plants described have been developed with economy of space as a majdr consideration. ~ d w e v e r where ample vacant land exists in close proximity to a factory, ash pondages similar to those

\


used by electricity authorities at modern coal fired generating stations are worth consideration.

Two Queensland sugar factories are well situated in regard to vacant land and have constructed pondages for the exclusive treatment of recirculating ash sluice water. The most recent of these handles all the ashes retrieved from a boiler station with a total 225 000 kg steam/h capacity. The ashes are sluiced to a common collection tank and pumped at a rate of 5 500 l/min to the ash pondage, 1 .4 ha in area. The retaining wall constructed of impermeable earthen material has a-gravel layer covering its upstream face in which i's buried a 500 min diameter perforated pipe running longitudinally along the wall. Connected to this pipe and running at right angles to it through the wall are a number of pipes of similar material. Downstream from the first wall is a second wall of a similar height, about 6 .4 m, such that an area of 0 .6 ha is retained between the two walls.

The ash from the sluice water discharged into the ash pond settles out in the large expanse provided. The 'clean'.water percolates through the gravel medium into the perforated pipes and so is delivered into the smaller clean water pondage. Froill here the 'clean' water is recirculated to the boiler sluices by pump. During operation a difference in operating levels between the two ponds of 500 mm can occur.

No operational problems have so far been experienced. However it has been found that the ponds have filled with ash at a rate considerably above that expected. A similar situation has arisen with the other ash pondage system for which a capacity of three crushing seasons was anticipated, while actual capacity appears to be about half of that. The height of the walls are to be increased for the 1977 crushing season because of this. This system has also suffered some problems in regard to blinding of the filter media with fine ash. These have apparently been eliminated in the newer installation by eliminating all fine gravel and imbedding the longitudinal perforated pipe closer to the inner wall.

Both systems have operated well and require negligible attention during the season. However the problems of removing large quantities of the ash from the dams durgin the off-season and disposing of it has yet to be undertaken. Any problems would be accentuated in this respect in a partic- ularly wet off-season.

CONC1,USFONS

The authors have attempted to cover the variety of ash handling plants existing in the Queensland sugar industry. From the range of equipment in use it is apparent that the type of ash plant employed is dependent upon:

i) The type of collectors fitted.

ii) The extent of available space.

iii) Capital cost of equipment.

iv) Expected operating and maintenance costs.

v ) Proximity of the factory to a township.


vi) Whether ash is to be transported separately or to be mixed with filter mud.

vii) Characteristics of the ash peculiar to the district and/or boiler installation.

The authors do not wish to convey the impression that all ash handling plants installed to date have been outstanding successes from the start. In fact several plants have been plagued with many troubles over a period of years and have managed to operate only by continuous purging. In these cases either ash settling area has been too small or ash removal capacity insufficient. Similar plants operating in different mill areas have received markedly different assessments of performance by their operating engineers. This only strengthens the authors views that each installation must be individually tailored to the application. It is hoped that some of the design data contained in this paper will assist in allowing more confident selection of factory plants.

I REFERENCES

1 . Cullen and Ivin. (1974). Recent tests on multi cyclone fly ash collectors, Q.S.S.C.T. 41st Conf., 133-141.

2. Flood, Honey and Munro. (1974). Emissions from bagasse fired boilers. Proc. I.S.S.C.T. 15th Conf. 3, 1680-1687.

3. Jacklin and Arrowsmith. (1970). The single boiler unit at Pleystowe, Q.S.S.C.T. 37th Conf., 257-265.

4. Hale and Whavman. (1969). Pilot studies on the settling of cane mads, Proc. Q.S.S.C.T. 36th7Conf., 283-243.

- 5. Sawver and Cullen. (1975). Dewaterine: of flv ash fr~m~banasse fired boilers. Proc.

Q.S.S.C.T. 42nd Conf., 311-317. - -

6. McDougall, Messiter and Sawyer. (1976). Racecourse ash handling system, Proc. Q.S.S.C.T. 43rd Conf., 157-163.

7 . Milford. ( 1976). Private commuiiication to Sugar Research Institute, Mackay. 8. Logan. (1973). A novel boiler ash removal system, Qld. Sug. Tech. Newsletter NO.

REVISION DE LOS SISTEMAS DE MANEJO DE CENIZAS EN LOS INGENIOS AZUCAREROS DE QUEENSLAND

G.M. Sawyer y R.N. Cullen

RESUMEN

Este articulo revisa las varias plantas de manejo de cenizas que han sido empleadas con las grandes calderas suspendidas modernas usadas en la industria azucarera de Queensland. Se hace referencia al trabajo de investigacidn llevado a cab0 l5or el lnstituto de Investi- gacidn Azucarera, Mackay, en este campo. Se discute sobre la quimi- ca de la ceniza del bagazo quemado en la caldera, y se enfatiza la naturaleza individual de cada instalacidn. ' \ ,, ';

3 < '

Factory Engineering A REVIEW ASH HANDLING … Sawyer A Review of Ash... · A REVIEW OF ASH HANDLING...

Documents

Transcript of Factory Engineering A REVIEW ASH HANDLING … Sawyer A Review of Ash... · A REVIEW OF ASH HANDLING...