Hot-Air - Dried Copra

Cheap Ceylon Driers Successfully Tested in New Guinea

A DEVELOPMENT in connection with the production of hot-air-dried copra in New Guinea will be of interest to all coconut planters.

As everyone knows, the world market has more or less rejected smoke-cured copra and the cheaper grades generally, but is disclosing an increasing demand for hot-air-dried: and the difference in price is now so marked that many plan ters are giving most serious consideration to the problem of installing efficient driers. The problem lies in the cost.

There are excellent driers on the market, but their price—running usually into hundreds of pounds—places them outside the reach of many planters, who have been hard-hit in recent years by the low returns from their principal product.

In New Guinea, they seem in a fair way to solving the problem. We are indebted to Mr. P. Coote, manager in Rabaul for Messrs. Burns Philp and Cos. Ltd., for the following information. A number of plan ters in New Guinea have installed or are installing what are called the Ceylon driers: and those who are operating them definitely are getting the hot-air rate for their copra.

The movement started about 1930, when Mr. B. Bunting, who has an expert knowledge of tropical agriculture, visited Ceylon and, as a result of his careful in spection of coconut plantation methods there, wrote an excellent pamphlet. Mr.

Coote thought much of this pamphlet, and had copies made and distributed among New Guinea planters, directing particular attention to the Ceylon method

of drying copra. Not much notice was taken of the pamphlet then; the planters generally were making large profits by following their old methods, so why should they worry?

But two planters in the Madang dis trict, Mr. E. V. O’Brien and Mr. E. J.

Wauchope, who are known for the effi ciency which they maintain on their plantations, were interested in Mr. Bun ting’s description of the hot-air driers in. use in Ceylon, and they decided to experi ment. Mr. O’Brien started it, and report ed considerable success; and Mr. Wau chope soon afterwards followed suit. Mr.

Wauchope recently wrote a pamphlet, describing his methods and results, and copies of this have been distributed by Messrs. Burns Philp and Cos., Ltd., Ra baul, who are doing everything possible to assist planters to produce the hot-air grade.

Mr. Bunting, in describing the whole of the Ceylon industry, laid down the gene ral lines followed there in the construc tion of driers; and both Mr. O’Brien and Mr. Wauchope introduced variations of their own, to meet the local conditions.

The type of drier described by Mr, Bun ting was built of brick, faced with cement with a corrugated iron roof and a con crete floor. It was 60 feet long by 24 feet wide, with a drying platform 60 feet long by 16 feet wide. It was divided into five bays, or rooms. In each room, there fore, the drying platform was 12 feet long and 16 feet deep, and in front of each platform was a space, which was called a verandah, 12 feet long and 8 feet wide.

Each bay could hold 8000 nuts, giving a kiln capacity of 40,000 nuts; but it is usually worked at half that capacity.

We now quote verbatim from Mr. Bun ting’s pamphlet; “The drying platform is constructed of iron girders, carrying wooden joists, spaced about 18 inches apart, over which are placed strips of areca-wood, roughly 1½ inches x ½ inch, as close together as possible. The unevenness of the battens gives ample spacing to allow the heat to pass through to the drying kernels. In addition, No. 3 or 4 gauge wire mesh is placed on top and tied down with wire to prevent small pieces of copra falling through into the firing pit below. It is stated that this precaution saves a loss of about 1 h per cent, of copra. The plat form is placed one foot below the top of the front wall, which is 4 feet 3 inches above the verandah level.

“The firing pit is roughly 4 feet 6 inches below the level of the varandah so that the firing floor is about 8 feet below the level of the platform, which is considered the most suitable height. The firing pit is divided by a brick wall so as to form two compartments, one of two bays and one of three bays. Holes, about 3 feet x 3 feet at the front of the platform, one in each chamber, allow access to the firing pits, which are connected with the veran dah by cement steps. Shallow steps are also placed inside the verandah in front of each bay in order to facilitate placing the nuts on the platform. The lower half of the verandah is built up to a height of

about 5 feet, but the ends are left open.

The wall at the back of the platform is either pigeon-holed or not; and built right up the eaves to allow fumes and moisture to escape. A shallow jackroof, placed about 6 inches above the main roof, will answer the same purpose.

“When the nuts arrive at the kiln they are split in half, and, providing the weather is dry, placed on a cement bar becue for two days, but during wet weather they are placed straight on the kiln. The opened nuts, which have been partially dried in the sun, are placed hap hazard on the kiln to a depth of about 12 inches with ordinary crops. When heavy crops are obtained the nuts are stacked 18 inches deep on the plattorm but in this case they must be turned twice daily.

Under ordinary conditions nuts will re main on the kiln for four days.

“After two days on the kiln the shells are removed and the kernels transferred to the next bay for further drying, and so on until the fourth bay is reached, when the copra should be quite dry. The object of moving the kernels to the next section is to ensure evenness in drying.

“The firing is done by placing a double row of shells side by side, each shell fit ting closely into the next, across the floor of the firing pit. When the nuts have been partially sun-dried, the double rows of shells are spaced about 6 feet apart on the floor of the firing pit, but during wet weather, when the nuts are placed straight on the kiln, the rows of shells are spaced about 3 feet apart. The shells are lighted at one end so that the fire creeps slowly to the other end of the pit. The shells usually burn at the rate of 8 feet per hour, so that with a platform 16 feet wide one firing will take about two hours to complete. Firing goes on almost continuously, a fresh fire being started immediately the nuts have been turned over on the platform.

“During windy weather the entrances to the firing pits are covered with sheets of corrugated iron so as to prevent too much draught. It is most important that the shells used for firing should be quite dry, so as to produce as little smoke as possible, because if they are wet the smoke will discolour the copra.

“When the kernels are quite dry they are transferred to the copra store. This building, which is constructed of corru gated iron, is raised about 8 feet above the ground and has a wooden floor, on which the copra is stored until sufficient quantity is obtained to make a consign ment. By storing the copra in this wav it is kept free from mould.

“In dry weather, small fires are kept burning at night outside the kilns, and

copra stores to absorb dew. These fires are lighted early in the evening and early next mornipg, since little dew falls dur ing the night.

“It is considered that small kilns with a platform 40 feet x 15 feet placed in fields of 150 to 200 acres each, are prefer able to a large central kiln, since the for mer method tends to reduce the cost of transport of nuts.”

Mr. Bunting described the kilns on eight plantations, altogether, and there seemed to be variations on every one of them. In most cases, the split nuts were sun-dried for one or two days before be ing introduced to the hot-air drier. But the general principles followed were the same throughout. He emphasised that everywhere the effort was made to keep the two halves of the coconut intact, and they went into the copra bags as com plete halves. Any small broken pieces usually were removed and sold as a separate and cheaper grade.

Mr. Coote, in Rabaul, has samples of copra from the plantations of Mr. O’Brien and Mr. Wauchope; and it is noticeable that in each case the full half of the nut has been preserved intact, clean, and un stained.

Mr. Wauchope (of Awar Plantation, Madang) has built a drier, at a low cost, 60 feet long and 22 feet wide, divided into five rooms, following generally the lines given by Mr. Bunting. He has suc ceeded in getting first-class hot-air-dried copra without having to purchase an ex pensive drier. We are assured that the smaller driers can be built for less than £SO. and that it is practicable to build three or four, scattered over a large plan tation. thus materially reducing transport and allied costs.

Mr. Wauchope’s pamphlet was written with a view to helping his fellow-planters in these difficult times, and therefore we publish it in full, with acknowledgments to the writer:

Specifications

The drying bed is similar to the ordinary type of smoke drying bed, erected over a firing pit, 6 feet deep, 18 feet wide and 56 feet long. It pro jects two feet over each side and end of the firing pit which makes the overall measurements 60 feet long and 22 feet wide.

The bed is 8 feet above the floor of the drying pit, and the main bearers are quela posts, 2 2 feet long by 18 inches diameter. These bearers are supported by strong uprights, 2 feet above the floor of the building and 6 feet apart. They carry strong cross pieces, about 6 inches apart, on which are placed areca palm strips, two inches wide and two inches apart.

The space between the floor and the top of the drying bed, to a distance of two feet above the bed, is closed in with second-hand galvanised iron. Two pieces nailed sideways reach two feet above the bed. The drying bed is divided into five compart ments (hereinafter referred to as rooms) of vary

ing sizes, according to the drying conditions and the length of time the copra takes in the process of drying, The sizes of the rooms are as follows: No. 1 Room, 22 feet x 14 feet.

No. 2 Room, 22 feet x 13 feet.

First Day’S Drying

Both these rooms are used to receive the first day’s copra cutting, and the copra enters the building from the end of the bed and is placed shell downwards, thus permitting of full current of hot air to pass freely up and around the half nuts and eliminating all danger of sweating. If the nuts are thrown into the bed in haphazard manner, many will cup and sweat, producing useless copra.

The above rooms will hold 7,500 husked nuts in the half shell and when the beds are fully charged the half nuts are about one foot high. There is a doorway similar to a cellar door, with steps leading down into the firing pit. This portion of the drier is completely partitioned from the third room, and separate from other portions of the pit.

The half shells in the fire pit are placed in

double rows, shell into shell, across the 18 feet width of the pit, and each double row is 4 feet apart. Double rows of nuts are used in lieu oi sun-drying, preparatory to placing the half-nuts on the bed, the aim being to have the nuts over the hot-air dried as soon as possible, thus eliminating any outside moisture, etc. (Sun-drying is not practicable on Awar.).

The rooms are usually stacked ready for firing about 5 p.m., and double row firing goes on through the night until about 3 p.m. the following day.

It is essential that the shell used for firing is quite dry, allowing it to bum with a clear, smoke less flame. Should the lines of shell go out, they will smoke and produce smoke tainted copra.

The doorway into the firing pit acts as a ven tilator; also, two open spaces, six feet by two feet on the opposite side of the drying-pit, above the pit wall and located at the centre of rooms 1 and 2.

This provides sufficient ventilation to allow cold air to enter, and provide oxygen to the burning shell. In reality, the bottom sheet of galvanised iron is taken off and the open space acts an a ven tilator. The ventilators should be placed on the ground level, to allow the cold air to strike down to the floor of the firing pit. This air, being heated, will expand and penetrate through the copra. Smoke will creep along underneath the bed and find its way out at the sides. The doorway leading down into the firing pit has a curtain which is used as a screen during windy weather.

Room No. 3, 22 feet x 12 feet.

Second Day’S Drying

On the second day, the half-shells from roomg No. 1 and 2 are thrown haphazard on to the areca palm floor of this room, ana tnree single rows of cut half shells are constantly fired throughout the night and into the following day. In firing bays

No 1,2, and 3 the rows of shell are lighted at alternate ends.

Room No. 4, 22 feet x 11 feet.

Third Day’S Drying.

On the third day, the contents of room No. 3 are transferred into this room. The height of the half-shells in this and No. 3 room is about 2 feet.

Only one single row of shell is fired under thi.room. Rooms No. 3,4, aind 5 are partitioned ofi, and also each section of the firing pit is completely partitioned off, with galvanised iron, leaving one sheet off to act as a door into each firing pit, and one doorway leading down into pit No. 4 acts as an entrance for the firemen to charge the firing pit.

Room No. 5, 22 feet x 10 feet.

Fourth Day’S Drying.

On the fourth day, half-shells are transferred from No. 4 to this room and the full charge is about 3 feet high. One single row of shell is lit in the centre of the firing pit.

On the fifth day, the cured copra is thrown out onto clean dry coconut fronds, where it is cooled off, and any copra sticking to the shell is either released by giving the shell a sharp tap or by gouging it out with a knife. The shrinkage is very large by the time this room is reached, and green copra that was on a level with the edge of the half shell when being placed in room No. 1 has shrunk about i inch into the half shell. The copra has mostly left the shell by this time, and the act of throwing the half-shells onto the bomboms, whe?s dried, releases much more, leaving only about 20 per cent, to take out of the half shell.

Sufficient ventilation is essential and it is hard to overdo it. Draughts must be guarded against, but free entrance for cold air must be available or hot air will come out of the firing pit through the doors.

Constant supervision is necessary to ensure that the firemen do not allow the fires to go out and smoulder.

Plaited coconut fans are ideal to fan the fires to prevent smoking—that is, if the lines of shell have a tendency to burn poorly.

The lines of shell are set in trenches, much like spoon drains, 2 feet wide and 1 foot deep, so actually the bed is about 8ft. 6in. above the flame.

A temperature of about 150 degrees is main tained on the first day, and about 120 degrees on the second day and gradually reduced by cutting out lines of fires, until the last day.

The drying bed must be strong enough to hold up to 40,000 nuts, when fully charged.

On no account use damp shell, or smoked copra will result.

It is wise to leave all the shells, whether loose from the copra or not, until the fifth day, to en sure complete drying; an added advantage being that they retain a certain amount of heat, which provides air spaces for hot air to circulate amongst the drying copra.

I have had copra, in half shells, as high as 4ft. in the sth bed, and heat circulating slowly through from the single row of shells in the fire pit of No. 5 room.

Building Structure.

The building over the bed is composed of native material. Bush timber and sago palm thatching are the only material used apart from kunda (Lawyer vine) lashings and five and six inch nails. There is a door at each end —one to allow green nuts to be loaded on No. 1 and 2 beds and the other door to allow cured copra to pass out

for bagging.

The refuse shell from three coconuts will dry the copra contained in five nuts. Surplus is avail able for cook’s lines and fires, domestic uses, etc.

Field Work.

Basis of 7½ tons of hot air copra per week, or 30 tons per month.

Collecting, husking, carrying to drier and splitting 23 boys Boss Boy 1 Firing and bagging 6 „ Total 30 boys Copra can be bagged whole and weighs 14.5 bags to the ton.

Sick or light duty lines can be utilised in sort ing and examining the finished product and dis carding copra not properly cooked, which is rare when the drier is working properly.

One boy can collect, husk, and split 320 nuts to the drier daily when working within one mile and not more than V/ 2 miles radius from the drier, and 400 nuts when working close to the drier. It is not difficult for the average boy to husk 800 nuts per day if nuts are collected for him and he does not have to split or bag. Splitting, bagging and carrying represent 50 per cent, of the work.

Fuel problems are unknown, as each boy brings the fuel to the drier in the shape of shell each day.

There is more labour required with this method compared with other known kinds of hot-air driers, but in comparison with other hot-air kilns I find the Ceylon method requires only five more boys to cure 30 tons of copra per month. This is negligible, when costs of installation and up-keep are compared.

This drier cost £40 and the greatest expense was labour. The upkeep and cost of construction of a hot-air drier is huge when compared with this method, and if copra was worth £12 on the beach I would not build an expensive drier to cure copra but rather build better types of Ceylon driers. The fire risk is nil and boys cannot over load the fires, as they can with a smoke or hotair kiln.

A Smaller Drier.

I have another small drier which differs slightly from the description given by Mr. B. Bunting but the principle remains the same.

This drier has four beds 12ft. x 12ft.; each bed dries 4000 nuts in four days. The bed is 10ft from the bring pit and each end has a large door which is seldom shut. This drier makes perfect copra and is the best type of small drier on the Leylon principle I have yet seen.

The main bed is 48ft. x 12ft., divided into four rooms, each 12ft. x 12ft., and 10ft. from the firing Both sides are completely enclosed with gal vanised iron (old rusty, discarded sheets). At each end there is a door 10ft. x 3ft., with a bag curtain, let down at times to prevent draughts. Cold air enters each end through the doors and there is a 6-inch space all round, immediately under and at the edge of the drying bed.

The half nuts are placed shell down for the hrst day of drying and then haphazard. Two firemen by day, and two by night, do all the work on this drier. The shell consumption is greater than on the larger drier, but a slight surplus of shell results. It takes about five nuts to dry the copra contamed in six nuts on this drier.