THINGS I WORRY ABOUT
CP 61-37 Percent
III. OPERATION AS A 4TH BODY
Our most serious problem with the 4th body installation was that we had difficulty in removing condensate from the heat exchanger. We actually tried about 5 different arrangements for removing the condensate, including the installation of a gear type pump in the line, but none of our arrangements were satisfactory, and the only times that our final connection (into the bottom of the 4th body) allowed us to get capacity information on the installation were when the large set of evaporators be- came fouled and the increase in pressure drop allowed the condensate to flow through the meter. We made sugar at least 3 times in the pilot plant during the test period, and this was also a problem, since we did have to partially dissassemble the unit once and use water to melt the sugar. This pro- blem was due to a wide variation in feed and other operating conditions in the large evaporator; how- ever, it should not occur in a full size process unit.
We have reached the following conclusions from our testing of the process as a 4th body during a 23-day operating period:
A. The process should run several times longer than a conventional evaporator, and possibly for an entire grinding season as a 4th body without being "boiled out."
B. The apparent overall coefficients of heat transfer values ranged from 320 to 380 BTU/sq ft/
•F/hr.
C. The apparent evaporation rates ranged from 10 to 18 lb/hr/sq ft.
D. The capacity of this system as a 4th body does appear to be considerably greater than that of a conventional system, and the apparent overall coefficients of heat transfer and evaporation rates both indicate this to be true.
Since we are aware that there may be a great number of questions concerning this development, we will devote the remainder of time allowed for answering a few of these questions.
CORE SAMPLING OF LOUISIANA SUGARCANE - 1972 STUDIES Harold S. Birkett and John J. Seip
Audubon Sugar Factory Louisiana State University
ABSTRACT
Cane payment in Louisiana is based on a sampling system which still retains the concept of crusher juice quality (a holdover from the days of hand-harvested cane) with modifications for trash content and juice purity (to accommodate mechanical harvesting). With the current intensive field mechanization, and particularly under wet muddy field conditions, the present sampling system does not adequately reward premium quality cane nor penalize substandard material. In view of the limitations of the current system, studies at the Audubon Sugar Factory have continued with the goal of evolving a cane evaluation system which would: a) remove the judgement factor in selection and processing the sample, b) standardize the sample procurement and processing equipment, c) minimize personnel requirements, d) divorce the system from mill operations, 3) provide a sample representative of the quality of the material in the cane con- signment, f) reflect the effect of trash in general and field soil in particular on juice quality and quantity, g) provide a measure of cane quality in terms of the estimated recoverable sugar in the cane, and h) for the processor, contribute to the factory chemical control and for the grower, provide a means for evaluating varietal selection and cultural practices. With the availability of commercial- scale core-samplers, sample disintegrators, and a vertical hydraulic press capable of exerting mill- scale pressures on a large sample, sampling studies initiated in 1953 were reactivated. The initial scope of the current investigations entails comparison of the quality of a cane consignment as de- termined by milling in the factory with that predicted by the conventional and by the core sampling technique. The core sampling system used in these studies proved simple, practicable, and meets many of the goals cited previously. Core sampling is superior to the conventional system as a sensor of juice quality due to the more representative nature of the sample procured by coring. While there is a variability among core samples from the same consignment, there is no bias relative to the location of the sample in the load. Processing the core sample in a 3-roll mill does not adequately reflect trash in the consignment when it includes a large volume of field soil. Such material washes out into the juice and does not appear in the sample bagasse as fiber or dry solids % cane. Preliminary tests with the vertical hydraulic press (which arrived too late to be incorporated into the complete test series) indicate that the press is a good sensor of juice quantity in that the press residue or bagasse retains much of the field soil in the sample. These studies should be continued in 1973 with the substitution of a hydraulic press for the sample mill as a sample processing device.
INTRODUCTION
General. Improved varieties and cultural practices in Louisiana have resulted in a significant improvement in the quality of the standing cane prior to harvest in terms of yield per acre and per ton of cane, disease, insect, and freeze resistance, and many other desirable features. Unfortunately, the increasing intensity of field mechanization in the form of larger and more powerful equipment, large farm units with the subsequent problems of harvest monitoring and discipline, and adverse climatic conditions of the past 3 crops have contributed to a marked increase in the volume of field soil, foliage, loose tops, and stubble, and of mangled cane accompanying the cane consignments to the factory.
Adequate evaluation of cane for payment with the current sampling system is particularly difficult under such conditions. As a result, the grower delivering superior quality cane is not being adequately rewarded, and by the same token substandard cane is not properly penalized. We appear to have arrived at the point where there is little incentive for harvest control and discipline, and as a result the entire industry suffers.
The Current Sampling System. The Louisiana system of cane sampling and testing for cane payment re- tains the concept of normal (undiluted) juice quality as a basis for cane evaluation and standard tons as the criterion of cane quality upon which payment is based. The factory normal juice brix is calculated from the crusher juice brix, and the factory normal juice sucrose (pol) is determined from the identity that the dilute or mixed juice purity equals normal juice purity. As originally implemented in the days of hand-cut cane, a grower's standard tons were calculated from his delivered tons, his crusher juice pol, the crusher juice sucrose factor (which related the factory normal to crusher juice sucrose or pol), and tables for converting the grower's normal juice sucrose to standard per delivered ton.
With the advent of mechanical harvesting, the practice of washing cane on the feeder table, and the return of cush-cush prior to the crusher, the system has been modified to provide for the removal of cane samples from the feeder table or vehicle, trash samples, and the inclusion of a juice purity factor (to account for the extraneous material accompanying the cane), and sucrose samples to be ground in a sample mill (to eliminate the dilution effect on crusher juice of the cane wash water and cush-cush). Incorpo- rating a sample mill into the system has necessitated additional factors. One is the dilution compensation factor, which relates the sample mill juice brix to that of the undiluted crusher juice. This is deter- mined periodically without any wash water or cush-cush prior to the crusher. With this factor it is
juice brix. Additional factors are the sample mill brix and sucrose factors which relate the factory normal juice brix and sucrose to that of the sample mill. From these factors, the grower's gross cane delivery, his trash and sample mill inspections, and tables for converting his normal juice sucrose and,
An Idealized Cane Sampling System. Among other things, an idealized cane sampling system for payment should:
1. Provide a sample representative of the quality of the cane in the consignment.
2. Remove the judgement factor in selecting and processing the sample.
3. Standardize the sample procurement and processing equipment and procedure.
5. Reflect the quantity of juice in the cane as well as quality.
6. Express cane quality in terms of recoverable sugar in the cane consignment - a criterion meaningful to both the factory and the grower - and minimize the number of factors necessary to determine the cane 7. Separate the sampling system from the mill operation.
8. Supplement chemical control data for the factory and provide meaningful data for the grower relative to his varietal selection and cultural practices.
EQUIPMENT AMD PROCEDURE
The Farrel Sample Mill. All core samples and the conventional sucrose samples were processed on the hydraulically loaded 3-roll (12 in. dia. x 12 in. long rolls) Farrel sample mill.
The Audubon Sugar Factory Mill. After sampling, the cane consignments were processed in the Audubon Sugar Factory Squier mill, which consists of 2 sets of knives, a 2-roll crusher and 3-roll mills (18 1/2 in. dia. x 24 in. long rolls).
The Vertical Hydraulic Press. Because of its late arrival, only a few screening runs were made on the Pinette-Emidecau Type OB102 hydraulic press. This press has a 5 11/16 in. dia. x 6 1/8 in. long perforated cylinder and a piston capable of exerting a maximum pressure of 3600 psig. (Because of the Farrel mill for sample processing in the 1973 studies).
The Core Sampler. Cane in the field carts was sampled by means of a J & L Model X-2 core sampler equipped with a Reitz Model PB10 prebreaker for sample preparation. The X-2 core sampler is an electro- pneumatically operated device with an 8 in. dia. coring tube which enters the cane delivery from top to bottom with an inclination of 45° to the vertical plane. this equipment is located at the Cinclare factory.
Miscellaneous Equipment. For removal of trash samples from the cane on the feeder table, a hydrau- lically operated mechanical grab was used. Transfer of the cane consignment and core samples from Cinclare to the Audubon Sugar Factory was accomplished by means of a 2 1/2 ton truck.
Cane Supply. Mechanically cut and loaded cane was procured from the Cinclare factory cane fields. It was transferred to the coring station by tractor-drawn field carts in 2-to 3-ton slinged bundles.
Cane Sample Procurement. As finally evolved, the cane sampling procedure entailed removing 3 core samples, one each from the back, middle, and front of the bundle, with the front being the end toward the tractor. The individual samples, weighing about 30 lb each, were placed in plastic bags and trans- ferred to the truck for delivery to the Audubon Sugar Factory along with the cored cane consignment.
Core Sample and Cane Consignment Transfer. After coring, the bundle was transferred to a truck and delivered to the Audubon Sugar Factory along with the indivudual core samples.
Sample Removal at the Audubon Sugar Factory. After breaking the bundle on the feeder table, one trash sample of about 100 lb was removed by mechanical grab, and 3 hand-grab sucrose samples were removed from different locations in the cane m a t / Each sample weighed about 30 lb.
Processing the Core Samples. Each core sample was removed from its plastic bag and passed 4 times through the Farrel mill. Cane, juice, and bagasse weights were determined, and juice and bagasse samples were
Processing the Trash and Sucrose Samples. The trash samples were processed in the conventional manner for determining trash % cane. Each sucrose sample was passed once through the Farrel mill and a juice sample removed for analysis.
Processing the Sampled Cane Consignment. After removal of the samples, the cane was processed in the factory milling tandem with the addition of 20% maceration water and a last mill roll speed of 30 fpm.
During milling, samples of crusher and last roll juice and bagasse were removed and composited. Fol- lowing the run, bagasse and juice weights and maceration water were determined. Samples of mixed juice were removed from the weighing tank, and the crusher, mixed, and last roll juice, and the bagasse samples were transferred to the laboratory for analysis.
Analyses. Juice analyses included brix by hydrometer and pol by the H o m e dry lead method. Bagasse was analyzed for moisture with the Dietert Model 278A Moisture Teller. Pol in bagasse was determined by the wet disintegrator method in which 100 g of bagasse were mixed with 1000 g of water (to which 0.25 g of Xa2C03 had been added) and disintegrated in a 1-gal Waring blender. The juice extract after 10 min of blending was then analyzed for pol_by the conventional method. Brix in bagasse was calculated from the pol and the mill juice purity (last roll juice for the factory mill and extracted juice purity for the Farrel mill). Fiber was by the indirect method, i.e., 100.000 - (Moisture + Brix).
AREAS OF INVESTIGATION
Correlation of Sample with Factory Mill Data. Core and conventional sucrose sample juice quality as brix and pol was compared with that of the factory crusher juice. Juice quantity was compared by way of cor- Variability Among Core Samples from the Same Vehicle. The variation in cane quality and related parameters was investigated by way of correlations among the 3-replicate core samples from the same vehicle. Addi- tionally, correlations were developed to indicate any bias as a function of the location of the core sample.
Application of the Core Sample System to a Cane Evaluation Scheme. A theoretically recoverable-sugar formula was developed based on the core sample data and assumed extraction and boiling house performance.
The resultant cane quality was expressed as lb 96° sugar per ton of cane. The theoretically recoverable sugar from the core samples was compared with the predicted sugar yield from the factory mill data. This comparison took the form of a liquidation factor which related the sum of the predicted sugar yields from coverable sugar was determined for the core data from each run. In practice, such a corrected sugar recovery would be used as a basis for cane payment.
Observations on the Conventional Sampling System. For those runs in which 3-replicate sucrose samples were taken from cane on the feeder table, the variability in juice brix and pol among the samples was analyzed and compared to that with the 3 core samples. These data were incorporated into sample mill brix and sucrose factors to see which system gave the most consistent factors.
Reproducibility and Accuracy of the Trash Sample. Since the conventional trash determination is in effect
Correlation of Cane Quality by the Current Sampling System with That of the Factory. A correlation was derived relating cane quality from the conventional sampling scheme in terms of commercially recoverable sugar with that predicted from the corresponding factory run.
Run Date 1 10/18 2 ]O/20 3 10/27 4 11/ 3 5 11/ 7 6 11/ 9 11 11/30 12 12/ 5 13 12/14 Average Standard de Coefficient
Accumul
0 0 2.77 3.63 3.83 3.83 9.24 10.58 13.35
viation of vari
ated Crusher
19.12 18.56 18.74 19.82 16.94 16.96 16.28 14.56 14.08
ation
Core Brix 17.75 16.97 18.53 18.81 16.35 15.42 15.56 14.06 13.46
Factor 1.0772 1.0937 1.0113 1.0537 1.0361 1.0991 1.0463 1.0356 1.461 1.0555 0.0290 2.75
Suc
19.24
-
18.79 20.41 16.96 17.19 17.59 16.26 16.45
rose Factor 0.9938
-
0.9937 0.9709 0.9986 0.9868 0.9257 0.8954 0.8559 0.9526 0.0539 5.66
* All sample data are the average of 3 samples except Run 1 (one sample), Run 2 (one core sample and no sucrose sample), and Run 5 (2 core samples).
The brix factor (crusher juice brix/sample mill juice brix) is in effect the dilution compensation factor (DCF). For factories which wash their cane - resulting in a dilution of the crusher juice - the DCF is a means of calculating an undiluted crusher juice brix from the corresponding 24-hr average sample mill brix.
Numerous questions have been raised as to the reproducibility of this factor. From the above data, the core sample factor shows only 1/2 the variability of the factor as currently determined from the sucrose sample, i.e., a coefficient of variation of 2.75 vs 5.66.
Table 2 shows the correlation between the crusher juice pol and that of the core and the sucrose sample in terms of a pol factor relating the crusher to the sample data. These data indicate greater variability in pol than brix. Again, though, the coefficient of variation for the core sample is less than for the sucrose sample.
RESULTS
Correlation of Sample With Factory Data. The factory mill analyses are shown in the Appendix, Table A-l. For each run, the average of the analyses of the replicate core samples was compared with the cor- responding cane quality parameter from the mill. The following correlations compare factory and core sample juice quality and quantity. Sample juice quality is compared with that of the factory crusher rather than mixed juice, since the latter reflects dilution due to maceration. The correlation is in terms of a brix factor relating the factory to the sample data as factory/sample. Table 1 shows the cor- relation between factory crusher and core sample brix. For comparison, the brix from the average of the 30-lb sucrose samples from each of the consignments is also shown. The statistical correlation of the data is in terms of the standard deviation, (S.D.) and the coefficient of variation (C.V.). The latter is the standard deviation divided by the average value for the samples and expresses the standard deviation as a percent of the average value.
Table 1. Correlation of juice quality as brix; crusher vs core and the conventional sucrose sample.
Table 2. Correlation of juice quality as pol: crusher vs core and the conventional sucrose sample.
The coefficient of variation of 12.67% compares with 2.75% (brix) and 4.82% (pol). Juice quantity is thus more difficult to predict accurately than quality. This would appear to reflect the volume of field soil in the samples. 1972 was a rainy season and numerous core samples were observed to be loaded with field soil. In the factory runs, with maceration, much of this soil washed into the juice and did not appear in the bagasse. This was also a problem with the core samples on the Farrel mill, though to a lesser extent due to the absence of maceration water.
Due to the late arrival of the hydraulic press, only a limited number of samples were processed in this equipment. These limited data showed a considerably greater field soil retention in the pressed bagasse (residue) than in the Farrel mill sample bagasse. The press thus appears to be a better trash sensor than the small mill. This will be investigated further in the 1973 studies.
Variability Among Core Samples From the Same Vehicle. As noted previously, the core samples were re- moved from the back, middle, and front of the bundle on most runs and processed separately in the Farrel mill. While the loading of the current 5-to 9-ton chain-net field carts and larger truck-trailers is reasonably random, such is not the case with the 2- to 3-ton slinged bundles used in these investigations because of the method of transferring the cane from the heap row to the cart. This was recognized as a
Run 1 2 3 4 5 6 11 12 13
Date 10/18 10/20 10/27 1 / 3 11/ 7 11/ 9 11/30 12/ 5 12/14 Average Standard devia Coefficient of
Accumulated rain (in.)
0 0 2.77 3.63 3.83 3.83 9.24 10.58 13.35
Crusher
16.02 13.79 16.12 17.07 13.72 13.30 13.87 11.47 11.55
Cor Pol 14.38 11.68 15.40 15.83 13.09 11.35 13.13 10.17 10.00
Sampl Factor 1.1140 1.1807 1.0468 1.0783 1.0481 1.1718 1.0564 1.1278 1.1550 1.1088 0.0535 4.82
e*
Suc Pol 16.38 16.26 18.24 13.97 14.18 15.40 13.75 14.05
rose Factor 0.9780 0.9914 0.9359 0.9821 0.9379 0.9006 0.8342 0.8221 0.9228 0.0656 7.11
* Sample frequency the same as in Table 1.
Tables 1 and 2 indicate that the core sampler is a better sensor of juice quality than the current sucrose sample. This would partly be explained by the presence of trash in the core sample, which also enters the crusher but is present to a much less degree in the sucrose sample.
Correlation of the juice quantity in the cane is shown in Table 3 as a bagasse factor relating the factory to the core sample bagasse % cane.
Table 3. Correlation of juice quantity as bagasse % cane: factory vs core.
Run 1 2 3 4 5 6 11 12 13
Date 10/18 10/20 10/27 11/ 3 11/ 7 11/ 9 11/30 12/ 5 12/14
Accumulated rain (in.)
0 0 2.77 3.63 3.83 3.83 9.24 10.58 13.35 Average
Standard deviation Coefficient of variation
Trash
12.62 40.86 11.46 4.00 12.00 6.00 14.00 5.50 19.23 13.96
Bagas
34.14 47.85 34.22 31.29 32.30 31.89 29.21 26.27 31.35 33.17
Core 43.19 59.53 33.79 32.41 36.93 32.74 30.91 37.63 30.46 37.51
Factor 0.790 0.804 1.013 0.965 0.875 0.974 0.945 0.698 1.029 0.8992 0.1139 12.67