Search

Using motors rated from a fraction of a horsepower up to 3,000 horsepower, the pulp and paper industry is driven largely by electric power. This article gives the method of determining motor requirements for some of the more important applications in this industry.

THE requirements for electric power-in modern pulp and paper mills are increasing at greater rates than the requirements for thermal power. In consequence, the electric power that can be generated by the normal flow rate of process steam is becoming inadequate. Low-cost hogged fuel and mill waste are also no longer available in abundant quantities to generate the increasing unbalance in electric load with condensing steam. Therefore, mill operators are finding it more economical to purchase a portion of their electric energy from utility power systems rather than to operate their own generating equipment on more expensive fuels and with consequent heat loss to the condensing water.

This paper discusses the application of a thermodynamic method of measurement to determine the efficiency of boiler feed pumps in large and modern generating sets, and reasons for the development of the method are presented. The principle of the thermodynamic method is defined, and the difference between this method and the classical one is specified. A description is given of the instrumentation used when the thermodynamic method is applied. The results of thermodynamic measurements are analysed and discussed, and the calculated efficiency is compared with the efficiency determined when the classic method is used. The paper finally presents the programme of trials that were undertaken on the boiler feed pumps of modern units of Electricité de France.

The Refuse Disposal plant being erected at Edmonton for the Greater London Council is the first of its kind to be built in this country. It is designed to handle automatically 1333 tons of crude refuse every 24 hours, untouched by hand. The refuse is used as a fuel to produce steam for the generation of about 30 MW of electric power, the exact amount depending on the throughput and calorific value of the fuel. A brief description of the plant is followed by the reasons and economic considerations associated with the overall concept. Later a more detailed explanation is given of those aspects of the design which were influenced by problems peculiar to refuse handling and incineration. The roller type incineration grates and combustion chambers, which are suitable for handling metallic objects as large as bedsteads, are described and their combustion principles explained. The boilers, of which the grates and combustion chambers are an integral part, presented some problems in designing for satisfactory availability of the gas side of heating surfaces and for an economically justifiable life of certain critical parts; these problems are described and reference is made to the somewhat limited large scale experience available at the time of establishing the design. Other parts of the plant are also described where novel in design or application.

Life support systems for current manned missions consume material at a higher rate, typically 21 lb/man-day, than can be tolerated for long-term missions of the future; thus development of closed life support systems is underway. It appears desirable to utilize heat from thermal to electrical power systems in life support endothermic processes rather than electrical heating in order to reduce the total electrical power requirements. Consideration of waste water and urine treatment, and recovery of O 2 from CO 2 processes shows it is feasible to provide approximately 50% of the life support power requirement with heat from solar, isotope, and reactor dynamic power systems. For early capability manned orbiting systems, the life support power requirements are typically 50% of the total power requirement, so that thermal integration reduces the electrical power load approximately 25%. This is a significant reduction in such critical items as collector and radiator area and isotope inventory. For later, larger stations and manned interplanetary vehicles the life support power requirements will be a small fraction of the total electrical power requirement and there will be less incentive for thermal integration.

A thermoelectric generator has been combined with thermal energy storage to produce electricity during simulated 90-min orbits with 55 min of sunlight and 35 min of darkness. The experimental model has demonstrated the thermodynamic feasibility of converting solar energy to electric power for space application. The generator produced constant power (± 7%) during simulated orbits in a space chamber and has also operated successfully utilizing natural solar energy. Projection of the feasibility model indicates that a generator with an output of 150 w coupled with a collector-concentrator of 8-ft dia can be built. This system can operate with 0.50 orientation error with a specific power of 2.14 w/lb. Very precise orientation would reduce the area of the collector by 17.5% and increase the specific power, excluding orientation equipment, to 2.3 w/lb. Analysis of the system shows that the thermal storage feature has a significant weight advantage over electrochemical energy storage. This feature also makes the system feasible from an operational standpoint since temperature excursions and warm-up period after solar darkness are eliminated.

The results of a study of auxiliary power generating systems for a large 24-man space laboratory for the post-1970 time period are presented. Solar dynamic, nuclear Snap 8, and solar cell-battery units vere investigated as possible auxiliary power systems capable of generating 18 to 40 kw of electrical power. Tradeoffs in weight, cost, reliability, solar area deployed and/or radiator area were performed for the various systems. The power required for subsystem operation and experimentation was established at 27 kw. On the basis of the tradeoffs and the 27 kw design load, the solar dynamic Brayton system was recommended for the laboratory.

Since the original use of solar cells for electrical power generation in space, the state of the art in solar-cell arrays has experienced some significant advances. The solar cell itself has been improved in many ways. These improvements have increased silicon solar-cell efficiencies from roughly 5% to 11% in space sunlight. Material improvements have been made in silicon which have enhanced the resistance of silicon solar cells to particle radiation. The methods used to connect cells into modules as a building block for constructing large arrays have been improved also. New methods in the soldering of cells into modules have decreased the degradation of the cells resulting from handling and soldering. In addition, the successful fabrication of cells into modules has made possible the matching of cells by modules rather than by single cells. The methods used to mount the modules to the supporting structure have been improved by using better techniques and bonding agents. With the above advances, sun-oriented arrays have been built which approach 10 w/ft2 and 10 w/lb when operated in near Earth space (with no particle radiation damage). With further research and development, the watts per square foot, watts per pound, radiation resistance, and cost of solar-cell arrays may he optimized further.

electric power were abundant there. It is interesting to note that the first expansion of the chlorine industry followed a typhoid epidemic in Niagara Falls in 1912. The largest production increase, however, came about when the pulp and paper mills began installing small plants to produce chlorine for use as a bleaching agent. By 1930 the paper mills were consuming about 47 per cent of the total chlorine supply, with 30 per cent being used for the manufacture of chemicals, 14 per cent for sanitation and 9 per cent in the production of textiles.

Oil impregnated kraft paper is exclusively used for the insulation of high tension electric cable.In this case, for the sake of electrical properties high dryness is required so that vacuum drying process is adopted for this purpose to minimize the processing period and deterioration of insulating material.We briefly described here a theory to determine the exhausting speed of vacuum pump system.The exhausting speedG (l /mm) is given as follows;G=π/S0 (1 + d/Δ) L T1/T2 where S0 represents specific resistance of moisture diffusion in paper layer (min·cm/l), d : core diameter (cm), Δ : insulation thickness (cm), L : cable length (cm).T1 means the theoretical drying time, when the exhausting speed is supposed infinite, and it depends only upon insulation thickness when the initial and final moisture contents are given. Time T2 depends on the exhausting speed and total amount of paper to be dried. Vacuum drying time T is represented as ;T= T1+ T2In calculating the value of G, it is recommended to select T2/T1 epual to about 0.1.The vacuum pump system of the cable drying equipment should have sufficient exhausting speed above the pressures of 2-10 ×10-2 mmHg, and have to be designed so as to be able to treat a large quantity of water without trouble.

An instrument system (data-collecting devices mounted on a tripod platform) has been built for measuring currents and sediment motion within 2 m of the sea floor. The platform is an aluminum tripod capable of sinking to depths of 200 m and returning to the surface. This platform contains its own lighting system and electrical power. Twelve shipboard controlled electrical outputs provide power for the sensing elements. The system is capable of: ( 1 ) providing continuous observation of the sea floor by means of underwater television; ( 2 ) continuously measuring the velocity profile (6 current meters and 1 direction vane) within 2 m of the bottom; ( 3 ) taking, on command, stereophotographs of the bottom for determination of bed configuration; ( 4 ) sampling the suspended sediment within 2 m of the bottom, and ( 5 ) measuring water depth. All data are transmitted continuously to shipboard and recorded on paper tape. This system has been used on several occasions in inshore waters for continuous periods up to 32 h.

1. Introduction of the type GRU-2 “universai” hydro-cutting tool at slow-coking plant has enabled the rate of discharge to be increased by 40% and has reduced consumption of water and electric power by 30 to 40%. The yield of electrode-grade coke has gone up by some 8 to 10%. 2. By using the “bottom-to-top” method of discharge, the yield of electrode-grade fractions of coke can be increased by 3 to 4%. 3. Conveying petroleum coke within the plant by crude mechanisms increase the amount the coke that is crushed and pulverized. In order to preserve the electrode-grade fraction sizes of coke, scraper-conveyers should be replaced by belt conveyers and the number of steps in the conveying process should be reduced as much as possible.

G. B. Rosenblatt: I have recently interested myself in the electrification of the lumber industry, and looking at it as an outsider who is coming in, I have seen some things, possibly, that those who have grown up with the industry don't recognize.