When the manufacture of sugar was in its infancy the cane was passed through but a single mill and the defecation and concentration of the saccharine juice took place in a series of vessels mounted one after another over a common fire at one end and connected to a stack at the opposite end. This primitive method was known in [Pg 204] the English colonies as the “Open Wall” and in the Spanish-American countries as the “Jamaica Train”.
The evaporation and concentration of the juice in the open air and over a direct fire required such quantities of fuel, and the bagasse, in fact, played such an important part in the manufacture of sugar, that oftentimes the degree of extraction, which was already low, would be sacrificed to the necessity of obtaining a bagasse that might be readily burned.
The furnaces in use with these methods were as primitive as the rest of the apparatus, and the bagasse could be burned in them only by first drying it. This naturally required an enormous quantity of handling of the fuel in spreading and collecting and frequently entailed a shutting down of the mill, because a shower would spoil the supply which had been dried.
The difficulties arising from the necessity of drying this fuel caused a widespread attempt on the part of inventors to the turning out of a furnace which would successfully burn green bagasse. Some of the designs were more or less clever, and about the year 1880 several such green bagasse furnaces were installed. These did not come up to expectations, however, and almost invariably they were abandoned and recourse had to be taken to the old method of drying in the sun.
From 1880 the new era in the sugar industry may be dated. Slavery was almost universally abolished and it became necessary to pay for labor. The cost of production was thus increased, while growing competition of European beet sugar lowered the prices. The only remedy for the new state of affairs was the cheapening of the production by the increase of extraction and improvement in manufacture. The double mill took the place of the single, the open wall method of extraction was replaced by vacuum evaporative apparatus and centrifugal machines were introduced to do the work of the great curing houses. As opposed to these improvements, however, the steam plants remained as they started, consisting of double flue boilers externally fired with dry bagasse.
On several of the plantations horizontal multitubular boilers externally fired were installed and at the time were considered the acme of perfection. Numerous attempts were made to burn the bagasse green, among others the step grates imported from Louisiana and known as the Leon Marie furnaces, but satisfactory results were obtained in none of the appliances tried.
The Babcock & Wilcox Co. at this time turned their attention to the problem with the results which ultimately led to its solution. Their New Orleans representative, Mr. Frederick Cook, invented a hot forced blast bagasse furnace and conveyed the patent rights to this company. This furnace while not as efficient as the standard of to-day, and expensive in its construction, did, nevertheless, burn the bagasse green and enabled the boilers to develop their normal rated capacity. The first furnace of this type was installed at the Southwood and Mt. Houmas plantations and on a small plantation in Florida. About the year 1888 two furnaces were erected in Cuba, one on the plantation Senado and the other at the Central Hormiguero. The results obtained with these furnaces were so remarkable in comparison with what had previously been accomplished that the company was overwhelmed with orders. The expense of auxiliary fuel, usually wood, which was costly and indispensable in rainy weather, was done away with and as the mill could be operated on bagasse alone, the steam production and the factory work could be regulated with natural increase in daily output.
Progress and improvement in the manufacture itself was going on at a remarkable rate, the single grinding had been replaced by a double grinding, this in turn by a third grinding, and finally the maceration and dilution of the bagasse was carried to the extraction of practically the last trace of sugar contained in it. The quantity of juice to be treated was increased in this way 20 or 30 per cent but was accompanied by the reduction to a minimum of the bagasse available as a fuel, and led to demands upon the furnace beyond its capacity.
With the improvements in the manufacture, planters had been compelled to make enormous sacrifices to change radically their systems, and the heavy disbursement necessary for mill apparatus left few in a financial position to make costly installations of good furnaces. The necessity of turning to something cheap in furnace construction but which was nevertheless better than the early method of burning the fuel dry led to the invention of numerous furnaces by all classes of engineers regardless of their knowledge of the subject and based upon no experience. None of the furnaces thus produced were in any sense inventions but were more or less barefaced infringements of the patents of The Babcock & Wilcox Co. As the company could not protect its rights without hurting its clients, who in many cases against their own will were infringing upon these patents, and as on the other hand they were anxious to do something to meet the wants of the planters, a series of experiments were started, at their own rather than at their customers’ expense, with a view to developing a furnace which, without being as expensive, would still fulfill all the requirements of the manufacturer. The result was the cold blast green bagasse furnace which is now offered, and it has been adopted as standard for this class of work after years of study and observation in our installations in the sugar countries of the world. Such a furnace is described later in considering the combustion of bagasse.