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1985 Technical Papers
San Antonio, TX
7th Annual Meeting
Microprocessor Control Advancements
Author: P. G. Szymaszek
The task of replacing an electro-mechanical or programmable controller control system with a microprocessor is relatively simple. The motivation for this conversion from the manufacturer's viewpoint has many reasons. First, the microprocessor system is cost effective. The high volume production of these electronic devices gives them a cost advantage. Secondly, the microprocessor system is reliable. This is an attribute of solid state electronics. Thirdly, microprocessor systems provide analog signal monitoring and computer interface capability economically. These advantages are significant but has the vast inherent power of the microprocessor really been fully utilized?
Clean Refrigeration Piping Systems
Author: Donald F. Ballou
For over a century now, owners and operators of large industrial refrigeration installations have considered sticking solenoid valves, hung up floats, plugged strainers and changing dirty oil, normal and routine maintenance. These are all normal maintenance chores and expenses when the installed system is internally dirty. We have all been guilty of accepting the above as normal when indeed a clean refrigeration system will eliminate most if not all of the above system difficulties.
Problems and Solutions with Ammonia Refrigerating Systems
Author: John Balsavage
I want to stress, that in your search to be innovative in simplifying new and old refrigeration systems to make them more efficient, please, use a qualified company with a proven history of efficient system design, and successful system renovations. It is important to have a qualified, proven contractor because we all make mistakes or under estimate a given problem. Processing facilities know the importance of getting their refrigeration system back on line after a shut-down. If a mistake has been made a plant manager or plant engineer needs to know that his contractor will have the manpower, technical knowledge and financial integrity to correct the situation without any excuses or waste of precious time.
Gazing into the Crystal Ball - 1985
Author: George C. Briley
Some 10 years ago, in conjunction with the activities of the "R" in ASHRAE committee, I wrote an article for the ASHRAE Journal which discussed the industrial refrigeration industry including some of the rather interesting developments that had taken place over the last 10 years (1964-1974) and predicting some of the developments that would evolve during the next decade -- and become viable in the marketplace.
Screw Compressors in the Food Industry with Particular Attention To Oil Cooling
Author: Anders Lindborg
Screw compressors have now become quite common within the food industry. Since their first appearance several important improvements have been made. Most of these are well covered in the literature. Here principally different ways to cool the oil of the compressor are discussed: i) in a water cooler, ii) by direct injection of liquid refrigerant and iii) in a separate heat exchanger cooled by evaporating high pressure refrigerant. Unrealistic catalogue data of compressors with direct injection are discussed. Experience from plants with capacity shortages of 15% is reported.
Mechanical Implications of Various Oil Cooling Methods on Screw
Author: Birger Grinneby
The use of liquid injection to cool a screw compressor is only a method to reduce cost of the initial installation. This cost reduction when compared for example to thermosyphon is very questionable, considering loss of efficiency and high risks of premature breakdowns that will be carried by the ultimate owner and operator.
The Second Biggest Problem with Evaporative Condensers
Author: W. Thomas Straehle
To produce full capacity an evaporative condenser requires large quantities of air at the lowest possible entering wet bulb temperature. In this paper we try to provide the necessary guidelines to insure this goal is obtained thus preventing the capacity robbing effects of recirculation of the hot discharge air. No installation will be 100% free, 100% of the time from some small amounts of recirculation; but following these recommendations will provide installations with practical layouts, and trouble-free operation.
Two-Stage Screw Compressor Systems
Author: Robert A. Hall
Why should a two-stage screw compressor system be any different than a system using reciprocating compressors? The main reason is simply because a screw compressor, unlike a reciprocating compressor, has the ability to operate single-stage at virtually any compression ratio within the standard refrigeration field of application. Although the screw compressor has the capability of operating single stage at very high compression ratios, obviously the cost of doing this, because of extreme HP situations, creates a natural limitation for single staging; in essence, the same limitation as reciprocating compressors. In this presentation we will investigate ten (10) completely different layouts utilizing screw compressors with ammonia at -40F suction and 185 lb. condensing, for a system that requires 100 tons of refrigeration. For the sake of comparison, we will list these ten examples, starting with the system that has the lowest possible initial cost with the highest BHP, and end up with a screw compression two-stage system that has the highest initial cost but the least BHP.
Hydrotreated Oils for Ammonia Refrigeration
Author: Glenn D. Short
The development of high quality ammonia refrigeration oils using hydrotreated oligomers of alphaolefins (PAO), synthetic hydrocarbon fluids, and from hydrotreated high viscosity-index (HVI) base stocks is described. The characteristics of the base stocks and the relation to performance in ammonia refrigeration systems is discussed. Comparisons to conventional naphthenic refrigeration oils are made. These hydrotreated base stocks provide several performance advantages through better thermal and chemical stability, less solubility with ammonia and excellent viscosity temperature characteristics.
A Critical Look at Old Habits in Ammonia Vessel Specifications
Author: William V. Richards, P .E.
This discussion of vessel design and specification will start with brief considerations of safety. For this, there is only one game in town: the unfired pressure vessel code of ASME, quite in a class by itself. In existence for 70 years as a voluntary standard, it is prime reference for building codes and safety standards around the world. In the United States, there are 2200 shops that have "U" stamps, supported by quality assurance programs and third party inspections assuring high standards of construction. To the extent that it is difficult to recall a single failure of a vessel due to fabrication defects. A second aspect of ammonia vessel design and specification, which we will discuss in detail, is vessel performance. In this regard, much of what you "old ammonia men" have learned has been by experience. However, this experience is not documented in the literature. Also, some bad habits die hard, as successive generations of young engineers have copied the habits of the older generations. Therefore, we offer some examples of these "practices", which can be critiqued in terms of the developments of recent years. Although variations possible in vessel design are more numerous than can be discussed in short summary, certain practices persist as a nuisance to plant operators. A sampling is offered in the following discussion.
Old But Still Smokin' (Rebuilding a Plant)
Author: Vito Lampugnano
Ashland Cold Storage is committed to a rebuilding program to increase the efficiency of the present plant. This commitment was justified by several reasons including: 1) spiraling energy costs, 2) an update of antiquated equipment, 3) reduce downtime on equipment and 4) remedy existing problems in the plant piping system. This paper will show what is being done to accomplish the end result.
Thermosyphon Oil Cooling for Ammonia Screw Compressor Units
Author: Rudolph Stegmann
This paper discusses a specific indirect cooling method, thermosyphon oil cooling, a method which is rapidly gaining acceptance due to the numerous advantages over alternate cooling systems. Thermosyphon oil cooling requires a shell and tube heat exchanger, and employs thermosyphon principles to provide the necessary flow of high pressure refrigerant through the cooler.
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