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HomeMy WebLinkAboutA Zeolite Energy Storage Unit Study 1983A ZEOLITE ENERGY STORAGE UNIT by University of Alaska, Institute of Water Resources A ZEOLITE ENERGY STORAGE UNIT Daniel B. Hawkins George S. Mueller Institute of Water Resources University of Alaska Fairbanks, Alaska 99701 April 1983 A Zeolite Energy Storage Unit Daniel B. Hawkins George S. Mueller Institute of Water Resources University of Alaska Fairbanks, Alaska 99701 ABSTRACT Two zeolite energy storage units using Alaskan zeolites theoretically capable of storing 144,000 Btu and 600 Btu, respectively, have been constructed and tested. No energy storage was achieved with the larger unit because we could not heat the unit externally to a high enough temperature to achieve energy storage through dehydration of the zeolite. The smaller unit, which was heated internally, stored and released on rehydration 75% of the designed eneray storage capacity. The remaining eneray, though available, was not released because of incomplete rehydration of the zeolite bed. This problem can be solved by redesign of the hydrator. The zeolites mordenite and clinoptilolite from the Talkeetna Mountains and Iliamna Lake areas are capable of storing about 23 xcals/kg zeolite. This capacity compares well with that for commercially available clinoptilolite from the conterminous United States. The capacity, however, is a factor of 2 to 5 times less than that attainable with synthetic zeolites 5A and 13X, but synthetics are much more expensive ($2,000 to $4,000/ton versus $200/ton for the natural zeolites). The Iliamna Lake zeolite deposits can be mined economically because of their accessibility to water transport. We think it possible to mine, grind, size and deliver clinoptilolite or mordenite to Anchorage for about $200/ton, a price at or below that for similar zeolites from the conterminous United States. We think the zeolite storage units designed and studied here have promise for the storage of off-peak electric power and for subsequent use in space heating and drying applications. With minor modifications, our small-scale unit can be constructed for home use with an electric radiator. This device would store 15% of the energy used in heating the radiator to sufficiently dehydrate the zeolite. The remaining 85% of the energy would be released as sensible heat. The stored heat would be available as needed by rehydrating the zeolite bed. INTRODUCTION This study is the result of a research proposal funded by the Alaska Energy Center and subsequently administered by the Alaska Division of Energy and Power. Work began on this project in May 1981. It continued through January of 1982 at which time it was suspended pending resolution of details pertaining to the administration of the contract. Work resumed in August 1982 to the present. Problem areas to be addressed by the study were: Solar Collector: Type Operational characteristics Working fluid transmission system Storage System: Design of heat exchanger Configuration of heat exchanger Performance characteristics of heat exchanger Design of hydrator Configuration of hydrator Performance characteristics of hydrator Heat Pump: Capacity and performance of system Interface storage system with Nielsen-Zarling heat pump system Materials Grade Variability of zeolite grade throughout deposit Assessment of Lake Iliamna zeolite deposit as to grade, technical performance and transportation costs. Performance Behavior of different zeolites as a function of particle size. As seen above, originally this project was intended to investigate the use of zeolites as a means of storing solar energy. The project was conceived to tie in with the heat-pump experiment of Nielsen and Zarling (University of Alaska-Fairbanks, Alaska Energy Center Project). We thought to design a system like the Swedish "Tepidus" system (Scott,1980) but use zeolites rather than sodium sulfide as the energy storage medium. As our work progressed, it quickly became clear that high temperatures were required for zeolite dehydration and that the flat plate, solar collector used by the "Tepidus" system would be inadequate. We chose, therefore, to design and investigate a zeolite energy storage unit independent of the constraints of the solar heating and energy transfer methods used by the "Tepidus" solar heating and heat-pump system. Thus, there has been no attempt here to tie this work either to solar heating or to heat-pump studies. The data obtained, however, bear directly on the use of zeolites in such system. Throughout this project we have not deviated from our stated primary effort which was to design and test a full-scale zeolite energy storage unit. This we have done. BACKGROUND Because this study is primarily concerned with the hydration properties of zeolites, a brief review (excerpted from Hawkins, 1983) of the nature and properties of zeolites is included here. The references cited give a detailed discussion of these fascinating minerals. Zeolites are hydrous aluminosilicates similar to feidspars. Originally studied as vesicle fillings in lava flows where they are present as large, well-formed crystals, zeolites are most abundant in sedimentary rocks enriched in glassy volcanic material. In this setting, zeolites form during or after burial by the interaction of reactive aluminosilicate material, such as volcanic glass, with pore -2- waters. Formation of zeolites is favored by high pH and high activity of alkali ions in the pore water. Early formed zeolites such as clinoptilolite, phillipsite, or mordenite are commonly forerunners of other zeolites such as heulandite, analcime and laumontite. Although there are more than forty naturally occurring zeolites, only six are especially abundant: analcime, chabazite, clinoptilolite, erionite, mordenite and phillipsite. Of these six, clinoptilolite is probably most useful because of its abundance, availability and Properties. Extensive deposits of clinoptilolite exist in the western United States, Japan, Bulgaria, Soviet Union, Africa, and Central America. AN INTRODUCTION TO ZEOLITES An attempt is made here to. provide the nonspecialist with a general understanding of what zeolites are, the composition of the common natural zeolites, their occurrence, their availability, how they are mined and the quality of the product. The reader should consult the numerous review articles published in the last twelve years for more detailed information. These articles are cited in this paper and listed in the references. Zeolites are hydrous alkali and alkaline-earth aluminosilicates structurally related to quartz and feldspars. The name "zeolite" was derived from the Greek ZEIN (to boil) and LITHOS (stone), and refers to the property of these minerals to give off water when heated. For many years, zeolites were thought to be mineralogical curiosities which, though common, did not occur in sufficient quantities to be commercially useful. Since 1950 zeolites have been shown to constitute more than 90% of some sedimentary rocks and to occur worldwide. They are now recognized as abundant minerals having properties valuable to industry and agriculture. Composition of Zeolites. There are more than 40 species of natural zeolites. More than 100 species with no natural counterparts have been synthesized. The theoretical number of possible zeolite structures is very large (Breck, 1974). In spite of the structural and compositional diversity possible, only about eight natural zeolites are abundant: analcime, chabazite, clinoptilolite, erionite, heulandite, laumontite, mordenite and phillipsite. The most useful are chabazite, clinoptilolite and mordenite. Compositionally, zeolites can be grouped according to silicon: the ratio of silicon to iron plus aluminum (Si/Al+Fe*?) and potassium (K), sodium (Na) or calcium (Ca) content. In Table 1 (Hay, 1977) the essential compositions of the common zeolites are presented. Clinoptilolite and mordenite are silica-rich zeolites, heulandite and erionite are intermediate silica zeolites, and chabazite, phillipsite, analcime and laumontite are silica-poor zeolites. Within these three groups, mordenite is Na dominated, clinoptilolite is Na-K dominated, phillipsite is K-Na dominated, chabazite is Ca-Na dominated, analcime is Na dominated and laumontite is Ca dominated. The compositions affect the properties of the zeolites. For example, the high-silica zeolites are more stable thermally and in low-pH environments; K-rich zeolites tend to be good NHy” ion exchangers. Jon exchange, and water and gas sorption are probably the most important properties of zeolites for most applications. Formation of Zeolites. Although zeolites are common in lavas, only the genesis of zeolites in sedimentary rocks will be considered here. Given enough time (Triassic or younger), a silica-rich reactant (volcanic glass) in an appropriate chemical environment (marine, saline-alkaline or hydrothermal) will produce zeolites. Most zeolite deposits result from the alteration of volcanic ash (tephra) although a variety of other materials have served as reactants. For example, in the marine environment silica-rich shells of small marine organisms may be the source of silica for zeolite formation (Boles, 1977). Zeolites form most readily in an alkaline (pH 8) environment because the solubility of silica is greater than at lower pH conditions and thus the supply of this essential reactant is greater. Similarly, because Ca, Na, and K are needed, zeolites tend to form in those environments where these elements are abundant. The effect of time may be viewed as an effect of temperature. In hydrothermal systems where temperatures exceed 100°C, zeolites can form in a few hours. This is because the -A- solubilities of silica and other reactants are increased with increased temperature, and the rates of reactant dissolution and zeolite growth are increased (Hawkins, 1981). These factors lead to rapid formation of zeolites. As the temperature and concentration of the reactants decrease, the rate of zeolite formation decreases. The time required for zeolite formation in natural systems may range from a few hours at high temperatures to millions of years at low temperatures. Although a few Paleozoic laumontite occurrences are known, most zeolite-bearing formations are relatively young. This observation reflects the physico-chemical fact that zeolites are not thermodynamically stable alteration products of volcanic glass. Zeolites are metastable and convert to feldspars and clay minerals in the long term. Even though zeolites may not be the most stable minerals in a particular environment, the rate at which zeolites convert to the more stable phase may be so slow that the zeolites persist indefinitely. The absence of zeolites in geologically old sediments, then, may not be due to the failure of zeolites to form originally, but may be due to their failure to persist; they probably have been converted to feldspars and clay minerals. This tendency to transform in response to changing environmental conditions is seen in the mineral zonation of natural zeolite deposits. Occurrences As Hay (1977) has discussed, most zeolite occurrences in sedimentary rocks can be categorized into several types of geologic environments including (1) saline, alkaline lakes (closed hydrologic systems), (2) saline alkaline soils and land surfaces, (3) open hydrologic systems, (4) deep-sea sediments, (5) hydrothermal alteration zones, and (6) burial-diagenetic or metamorphic environments. These different environments commonly show characteristic patterns of zeolite zonation (see Fig. 1 and 2. Hay, 1977). These patterns are indicative of the response of the system to changes in the solution chemistry and temperature during zeolite formation. Zeolite occurrence in these different environments has been extensively reviewed (Sheppard, 1971-1973; Hay, 1977-1978; and lijima, 1980). Here are considered only those environments in which economic quantities of zeolites are found. -5- Saline, Alkaline Lake Deposits. Surdam (1977) and Surdam and Sheppard (1978) described zeolite formation in this environment. Relative to other deposits, the zeolite-bearing zones tend to be structurally simple, to be thin (several meters or less), to be several km? in extent and to contain high concentrations of zeolites. The higher-grade deposits of zeolites are common in this environment. Deposits of this type are restricted to arid regions. These deposits are good sources of clinoptilolite, chabazite, erionite phillipsite, analcime, and mordenite. A well developed zonation pattern typical of zeolite formation in this setting can be seen in Fig. 3 of Sheppard and Gude 1973. An example of such a deposit mined for its chabazite content is the Bowie, Arizona deposit (Sheppard et al., 1978). Open-System Type Deposits. Zeolite occurrence in open hydrologic systems has been described by Hay and Sheppard (1977), Sersale (1978), Istrate (1980). In this environment, large volumes of volcanic sediments have been transformed to zeolites by the action of downward percolating groundwater. Zeolite zonation tends to be vertical rather than lateral in response to the chemical change in the water with progressive alteration of the volcanic sediments. Zeolite-bearing horizons in this environment are tens to hundreds of meters thick. Zones containing up to 90% clinoptilolite or mordenite are common, and extensive economic deposits of these zeolites occur worldwide. In Italy, the interaction of groundwater and volcanic ash has produced chabazite and phillipsite. Where sea water has been involved, analcime was formed (Sersale, 1978; Scherillo and Porcelli, 1981). In Turkey, in a setting reminiscent of the southwestern United States, erionite and chabazite have formed (Mumpton, 1981). Because of size and grade, the zeolite deposits formed in open hydrologic systems constitute the major source of natural zeolites. Burial Diagenetic Deposits. Burial diagenetic deposits typically involve marine sediments. Because of their marine character, I have chosen to group within this environment deposits of zeolites in Japan and Alaska that Hay and Sheppard (1977) included in the open-system deposits. This difference in classification points up the fact that the boundaries between the different environments are not sharp and that some aspects of several environments are present in many zeolite deposits. Burial diagenetic deposits of zeolites have been discussed by Boles (1977b), Iijima and Ohwa (1980), and Dudley and Chent (1980). Zeolite strata in this environment are hundreds to thousands of meters thick and extend over areas of hundreds of km, These strata are recognized and mapped on the basis of the mere presence( e.a., a few percent) of zeolites. The thickness and areal extent does not mean that the rocks necessarily constitute high-grade deposits of zeolites. They can, however, in Japan and Alaska. Burial diagenetic deposits typically contain laumontite and, less abundantly, heulandite. These zeolites form in response to temperature- induced reactions produced by deep burial of volcanic debris. Thick sequences rich in laumontite are common, but because the properties of laumontite are less desirable than those of mordenite and clinoptilolite, the laumontite zones are of little economic significance. The presence of laumontite in sediments can be detrimental. In Alaska, many of the oil-producing horizons in the Cook Inlet consist of volcanic sands. In many places the volcanic ash in these sands has been converted to laumontite, which fills the pores of the sandstone and prevents the accumulation of petroleum in what would otherwise be excellent reservoir rocks. Heulandite is structurally similar to clinoptilolite and has similar though not identical properties. Heulandite is potentially a more useful zeolite than laumontite but large, relatively pure deposits of heulandite are rare and few, if any, are being mined at present. Silica-rich tuffs buried at shallow depths and, thus, under relatively low temperatures commonly produce thick, high-grade deposits of clinoptilolite and mordenite. The zeolite deposits of Alaska (Hawkins, 1976; Madonna, 1977) and many of those of Japan (Minato and Utada, 1971; lijima, 1971; Iijima and Utada, 1971) are of this type. These deposits are thick, several to many kin? in extent, and contain up to 90% clinoptilolite or mordenite. Unlike other types of deposits, these tend to be more complex structurally, with folding and faulting common as a result of the tectonic forces acting during burial and subsequent uplift. Hydrothermal Deposits. Zeolite occurrences in hydrothermal (geothermal) deposits have been reviewed recently by lijima (1978, 1980), Kristmanndottir and Tomasson (1978), and Sameshima (1978). Zeolites are common in gecthermal areas and generally show a characteristic zonation. Clinoptilolite and mordenite are found in the shallowest and coolest zones. Progressively deeper and hotter zones contain analcime, heulandite, laumontite, and wairakite. Although commonly high grade, hydrothermal zeolite deposits are limited both in extent and geographic distribution. Thus, they are generally of limited economic importance worldwide. Zeolites from these deposits may be important in Iceland and New Zealand, however. Availability Here, attention is focussed only on those types of zeolite deposits that are potentially economically exploitable. Zeolite deposits from open hydrologic systems are of the greatest economic importance, followed by deposits from saline, alkaline lakes and by certain burial-diagenetic deposits. Large quantities of clinoptilolite, chabazite, and mordenite are abundant throughout the world and commercial production is increasing. The capacity to produce natural zeolites far exceeds the present demand. There is no shortage of natural zeolites now, nor is a shortage likely in the foreseeable future. The occurrence and availability of natural zeolites worldwide with emphasis on deposits in the United States was reviewed by Mumpton (1981b). Tables 2, 3 and 4 (Tables 16, 17, 20, Mumpton, 1981b) list respectively: reported occurrences of sedimentary zeolites, countries currently engaged in zeolite mining, and zeolite Property owners in the United States currently engaged in zeoagricultural research efforts. Further information on the distribution and properties of selected zeolitic tuffs from the western United States has recently been published by Sheppard and Gude (1982). Production of Zeolites. Mining a zeolite deposit is simple compared with mining most other minerals. Because many zeolite-bearing -8- horizons are near the surface, only thin overburden must be removed to expose the ore. The zeolite-bearing horizon can generally be mined with a front-end loader. Beneficiation other than drying, grinding and sizing is not necessary for most applications. Natural zeolites are more variable in their properties than are synthetic zeolites. For certain applications, a clinoptilolite from deposit "A" may not be equivalent to one from deposit "B", but both may perform identically in other applications. When possible, the user should evaluate zeolites marketed by different suppliers as well as different lots marketed by the same supplier. The physical and chemical differences among them may be significant. Transportation of the finished product is a major cost in natural zeolite production. The market should be close to the source if costs are to be minimized. Because the cost of zeolites is also dependent upon the particular application envisaged, no attempt is made here to give specific prices, which can be obtained from suppliers. The production and marketing of natural zeolites was discussed by Mumpton (1981b) and recently by Leonard (1982) and Eyde and Eyde (1982). Health Aspects. The use of natural zeolites has been questioned because of the occurrence of mesothelioma (a malignant respiratory disease) among villagers in Turkey. It is suspected that the disorder is caused by exposure to dusts containing the fibrous zeolite erionite. Mumpton (1981a) and Rohl et al. (1982) discussed the postulated association of erionite with mesothelioma. No conclusive causal relationship was established. Suzuki (1982) carried out an experimental study in which erionite and fibrous mordenite were injected intraperitoneally into mice. Carcinogenic'and fibrogenic effects consistent with mesothelioma were observed primarily for erionite. The effects were similar to those of ashestos. Similar results have been found independently by Morisi et al. (1982), in which pleural mesotheliomas were produced in rats following interpleural injection with erionite fibers. Unlike the results of Suzuki, intraperitoneal injection of erionite did not produce mesothelioma, whereas injection of Crocidolite did. These data strongly suggest that erionite may act as a causative agent of mesothelioma.At present, there appears to be no cause to question the safety of nonfibrous zeolites such as clinoptilolite. -9- There is clearly a need for further research. Respiratory problems produced by long-term exposure to mineral dusts have been recognized for many years, and certain minerals such as quartz, amphibole, asbestos, beryl are more troublesome than others. Common sense dictates that respiratory protection should be worn when working with any mineral dust. Conclusions Points to leave with the potential user of zeolites are: Natural zeolites are an abundant, worldwide mineral commodity. Because of geographic distribution, size and grade of deposits, and properties, clinoptilolite is probably the most useful zeolite for agriculture. The user should keep in mind that the properties of natural zeclites may be quite variable among lots and among deposits of the same mineral. The cost of zeolites is apt to be lower the closer a user is to the source of supply. No evidence has been presented suggesting that the zeolites other than erionite and possibly fibrous mordenite may pose a health hazard. Clinoptilolite seems to be safe to use. -10- B. ENERGY STORAGE PROPERTIES As previously described , zeolites are hydrated minerals. Water is an essential part of their structure and is located in cavities within the alumino-silicate framework of the zeolite. This water can be driven otf by heating the mineral, leaving the anhydrous zeolite in an activated state. This state is maintained if the zeolite is cooled to ambient temperature in the absence of water. If water is now added to the zeolite, the zeolite spontaneously rehydrates, giving off heat in the process. This process of hydration and dehydration can be simply viewed as follows: Zeolite-nH,0 + heat = Zeolite* + Ho0 where Zeolite* indicates the dehydrated form of the zeolite. Unlike clay minerals and many hydrous salts that swell or shrink upon hydration or dehydration, there is no significant volume change in zeolites during hydration or dehydration. This is because the water is located within the rigid framework of the mineral rather than between discrete layers of the structure as in the case of clay minerals. This property of reversible hydration-dehydration accompanied by a large energy change and no volume change makes zeolites of interest as energy storage media as has been pointed out by Shigeishi et al. (1979) and Gopal et al. (1982). Although the principle of energy storage on zeolites is simple, there are many questions that must be answered before zeolites can be used in a practical energy storage device. The work undertaken here is akin to designing and building a flashlight. There are questions that pertain to the batteries, e.g., how many? Alkaline or Ni-Cad? -- and to the flashlight, e.g., how big? How bright? Waterproof? etc. With reference to this homely analogy, the choice and evaluation of zeolites is like the choice and evaluation of the batteries, while the design and construction of the energy unit is like the design and construction of the flashlight proper. For this reason, this report is divided into two -11- parts. One pertains mainly to the zeolites and the other pertains to the energy storage unit. Purpose The purpose of the zeolite part of this study is to evaluate the behavior of natural Alaskan zeolites as energy storage media. In so doing, the behavior of several synthetic zeolites and a commercially available natural zeolite (clinoptilolite-1010a, the Anaconda Company ) were also studied. Although many occurrences of zeolites in Alaska have been reported, and the potential for finding economic deposits of zeolites is high (particularly on the Alaska Peninsula and the Aleutian chain), only two deposits (Hawkins, 1976; Madonna, 1980) have been studied in detail. The major cost associated with the production and use of natural zeolites is the transportation cost from deposit to point of use. The Horn Mountains zeolite deposit (Hawkins, 1976) is relatively accessible by Alaskan standards, being only 9 miles from the Glenn Highway. It is accessible to 4-wheel drive vehicles via a "Pioneer" mining road. This deposit is not as accessible as the Lake Iliamna deposit, which occurs at or near shoreline. As Madonna has descrcibed, transportation from this deposit is relatively easy and inexpensive because of the 14-mile long truck road that connects Pile Bay Village on Iliamna Lake to Cook Inlet via Iliamna Bay. This road is maintained between May and October each year by the Alaska Department of Transportation for portage of fishing boats from Cook Inlet to Iliama Lake from where they proceed by water to Bristol Bay. If the Lake Iliamna zeolites are of comparable grade and quality to the mordenite from the Horn Mountains, then the Lake Iliamna deposits would be preferred because of ease of transport. Sampling. Both the Horn Mountain and Lake Iliamna zeolite localities were sampled. Because, the Horn Mountain deposit was more thoroughly studied, bulk sampling of this deposit was done so that sufficient quantities of material (several tons) would be available for use in the energy storage unit. A. — Horn Mountain deposit. Approximately 5,000 Ibs of mordenite- bearing tuff were collected from rubble crops along the strike of -12- this deposit. The tuff was simply loaded into bags and transported by helicopter to the Glenn Highway and then by truck to Fairbanks. B, Tliamna Lake deposit. This deposit has not been studied in as great a detail as the Horn Mountain deposit and it was not clear at the outset where the best material was located. It 4s usually not possible to determine in the field the type and quantity of zeolites present in an altered volcanic tuff. This requires x-ray diffraction studies in the laboratory. Various outcrops were sampled (See locality map, Appendix A.) that on the basis of field appearance showed promise of being zeolite-rich. Several 50 pound samples were taken from the most promising outcrops. This work was done by backpacking and was supported by a float-equipped fixed-wing aircraft. Thus, it wasn't possible to obtain large quantities of zeolites from the area. As a result, only laboratory were have been performed on the Lake Iliamna zeolites. Laboratory Studies All zeolite samples were ground to -325 mesh and examined by x-ray diffraction to determine the type and quantity of zeolites present. X-ray diffraction was done using a Rigaku "Miniflex" diffractometer with Ni-filtered copper radiation at 2 dea/min scan speeds. The results of the x-ray diffraction analysis of the various Lake Iliamna samples are shown in Table 5. The location from which these samples were taken are shown in Appendix A. Samples of the mordenite tuff from the Horn Mountains were x-rayed but the results are not reported here because all contained mordenite as the only zeolite and in the quantities expected (60-80% mordenite). Thermal Gravimetric Analysis Those samples that contained abundant zeolites were analyzed by thermalgravimetry (TGA) using a Thielco TGA-DTA unit. Essentially, TGA measures the weight lost by a 100 mg sample when heated at a fixed rate to a fixed temperature. In the case of zeolites, the results are a measure of the amount of water given off -13- by the zeolite at various temperatures. Differences in weight loss among different samples reflect the quantity and type of zeolites present. Those samples that lost the most water have the greatest potential for energy storage and were studied further by calorimetry. The results of the TGA measurements are shown in Appendix B. and C. Calorimetry To measure the heat of hydration of the various zeolite samples, a Parr stirring calorimeter was used. A vacuum train was constructed that permitted 1 gram samples of zeolite to be placed ina glass ampule and dehydrated under vacuum at 350°C for 24 hours. The neck of the ampule was sealed with a torch while the sample was under vacuum at high temperature. The ampule was cooled and placed in the calorimeter containing 100 ml distilled water. When the calorimeter was thermally equilibrated the ampule was crushed and the temperature rise resulting from hydration of the zeolite was measured. From calibration of the calorimeter by a reaction in which a known quantity of heat was released, the temperature rise was used to calculate the enthalpy of hydration of the zeolite. Besides the natural Alaskan zeolites, the natural zeolite clinoptilolite (TAC-1010A), the synthetic zeolites 5A(Ethyl Corp.) and 13X(Linde Corp.) were also studied. The results of the calorimetry measurements of these samples are shown in Table 6. Specific Gravity and Bulk Density The specific gravity of uncrushed fragments of mordenite tuff was measured on a Joly balance. The average specific gravity so measured was 1.97 +0.05 (mean +2 s.d.). The bulk or packing density of the ground zeolites was measured in various containers ranging from 35 mm film cannisters to a 30 quart pressure cooker. The average bulk density of the ene mordenite — loosely packed in a container is 1.0 g/em? + +.05 g/cm, -14- Thermal Conductivity The thermal conductivity for several zeolite samples was measured using a thermal conductivity cell constructed for the purpose (Crosby 1961). The cell consisted of an 8 inch long copper pipe, 14 inch inside diameter, capped at both ends. A small chromel-alumel thermocouple was centered in the cell and cemented in place with silicone sealant. The cell was filled with ground zeolite, the caps sealed with silicone and the cell placed in a boiling thermostated water bath. The temperature rise of the cell was continuously monitored with a strip-chart recorder. The thermal conductivity was calculated from the time-temperature data using Heissler charts to solve graphically the appropriate heat-flow equations. The thermal conductivity measured was 4.2 x 1074 sec! cm} deg = (.18 w m7! ecnty, No difference in thermal conductivity was observed for the different zeolites although the hydrated form of the zeolite tends to have a higher conductivity. cal Grain-Size Analyses We ground 4,300 pounds of Horn Mountain mordenite in a continuous jaw crusher to 4 mm or less diameter. The grain-size distribution of this material obtained by grain-size analysis of 6 1- pound samples taken at random from 6 of the 72 bags containing the ground zeolite is shown in Appendix D. The entire grain-size distribution was used in both the large and small energy-storage units. ENERGY STORAGE UNITS A. Design and Construction After several false starts, two energy storage units (large and small) were designed and constructed. Smal1_Unit. The small or “bench-scale" unit is shown in Appendix F. This unit consists of a common 30 quart capacity pressure cooker modified to accept a 110v household electric oven heating element, three thermistors, a hydrator tube, and a dehydration port. The pressure cooker was wrapped in 6 inch fiberglass insulation and placed ina galvanized garbage can. When filled with zeolites this unit contained =15= 24.2 kg (53.2 lbs) Mordenite, 21.8 kg (48 lbs) TAC 1010A, 9.77 kg (21.5 lbs) 5A. The unit has a design storage capacity of about 560 kcal (2200Btu) with Alaskan mordenite, 500 kcal(2000Btu) for the synthetic zeolite 5A and 410 kcal(1645Btu) for the TAC 1010A. The current flow to the heating unit was measured by means of a standard household electric meter. Temperature control and monitoring was done by computer control using a Commodore 64 computer with an HP digital voltmeter and electronic switching circuitry desianed and constructed by one of us (GSM). The mass of water removed on heating was continuously measured by means of a top-loading electronic balance. During heating, the valve on the hydrator is closed and the valve on the dehydrator tube is opened. Steam passes out through the condenser tube, condenses and is collected in the flask on the balance. When the zeolite bed is dehydrated while at high temperature, the dehydrator valve is closed thus "shutting in" the unit which is then cooled to ambient temperature. To hydrate the zeolite, the hydrator tube valve is opened and the water previously driven off is added through the hydrator tube. Water could also be added through the condenser tube, but the bed would not be as well irrigated as it is by passing water through the perforated tubing located within the bed itself. During dehydration and hydration, the temperatures were measured every minute and written to disk. The temperature was also printed out every 10 minutes so that a written record was also available. The thermistors were ordinary household oven thermistors calibrated against a standard laboratory thermometer both of which were calibrated at the normal freezing and boiling points of water. Temperature calibration at temperatures above 100° C was made against the calibrated thermometer while heating both thermistors and thermometer in an oil bath. Polynomial regression was used to obtain temperature versus resistance equations for the different thermistors. These equations were used to calculate the temperatures corresponding to the measured resistance of the thermistors. -16- Large Unit The large or full- scale unit is shown in Appendix E. This unit consists of a 500 gallon mild steel tank (Greer Welding, Fairbanks ,AK) containing a 3 inch i.d. copper tubing heat exchanger (supported on a 2 inch angle-iron frame),a 3 inch diameter hydrator tube, a 2 inch diameter dehydration pipe,and an outlet conduit for thermistor wires. The tank was supported on 2 inch cinder blocks and was placed ina 6x 6x7 ft. fiberglass insulated sheet-metal enclosure. The enclosure had a 20 inch by 30 inch rectangular opening at the inlet of the tank heat exchanger and a 12 inch duct opening at the top of the unit enclosing the outlet from the heat exchanger. Two, vented 55 gallon polyethylene drums used as hydrator barrels were situated above the insulated enclosure and were connected to the hydrator and dehydrator pipes. The overall height of the unit was 10 feet. Before connecting the dehydrator valve, 1,564 kg(3,440 Ibs) of ground mordenite (See Appendix D.) were added to the tank. The zeolite was settled into place by vibrating the tank and zeolite with a concrete form vibrator. The theoretical energy storage capacity of this unit with mordenite is about 36,000 kcal(144,000 Btu). Were the synthetic zeolite 13X used, the theoretical capacity for 1,560 kg would be about 315,000kcal (1,300,000 Btu). The unit contained 15 thermistors located internally, an additional 3 situated externally on the inlet to the heat exchanger, 3 more in the stack above the heat exchanger outlet, 1 in each of the hydrator tanks, 74 on the external faces of the insulated housing and 3 air-temperature thermistors located on a rod at 1, 7 and 10 feet above floor level. These 30 thermistors were monitored through a digital voltmeter, under the control of a PET microcomputer. The data were recorded every 10 minutes , printed out and written to disk. Originally, we planned to heat the zeolite bed internally by blowing hot air through the heat exchanger. The tank was to have been wrapped in fiberglass. However, we found that the heating unit we chose to use ( a 350,000 Btu/hr Reddy Heater) would not operate against a -17- backpressure. A "Herman Nelson" type heater, though able to work against a back pressure, could not reach the temperatures needed (150°C). We therefore heated the tank externally with the Reddy heater. The 6 x 6 x 10ft. unit was located in the high-bay garage of the UAF Fine Arts complex garage. The facility was shared with the library and the KUAC TV station. During operation of the unit, the hydrator valve was closed, the dehydrator valve opened, and the unit heated through the rectangular port by blowing hot air against the side of the tank at the inlet to the heat exchanger. It was necessary to provide "make-up" air for the heater in such a way that would not cause the pipes in the Fine Arts complex to freeze due to the influx of -30°F fresh air. A 4x 4x 30 ft plywood intake duct was constructed and installed with the inlet at the open garage door. The remainder of the door was blocked off with styrofoam insulation. This provided adequate make-up air for the heater and permitted it to be operated continuously for 12 hour periods at which time it needed refueling. During heating, the unit was continuously attended by us to insure that no fire hazard developed and that the system functioned properly. RESULTS Large Unit Three separate runs were performed with the large unit. The first was a 6-hour test run to see how the unit performed. The second was to have been a 48 hour run, but was aborted after 24 hours when concern was expressed by the Physical Plant personnel that the pipes of the building would freeze. The above described plywood duct was constructed and the final run carried out in which the unit was heated continuously for 43 hours. Only the results of this run are shown in Appendix G. -18- In these figures the solid line is the measured temperature. The three major valleys shown in several of the figures occurred when the unit cooled during refueling of the heater. The dotted peaks and valleys are spurious "switching transients" arising in part from our instrumentation and partly from the electronic environment in which the unit was operated. These spurious values could not be easily removed numerically during the data processing and hence were included in the final presentation. Several features of the temperature data are important. Note that the temperatures of thermistors 1 through 5 were high and that these responded like those on the inlet (thermistors 19-21) and in the exhaust stack (thermistors 16-18). The high temperatures and quick response to external temperature changes shown by thermistors 1-5 are results of the proximity of these thermistors to the heat-exchanger outlet, to only a thin layer of zeolites covering these thermistors, and to convective heating of the thermistors by air trapped at the top of the tank. There is a disparity between the temperatures measured at the inlet by thermistors 19 and 20, and that measured by thermistor 21. The latter thermistor pointed upwards and was in the top part of the hot air stream from the heater. The former thermistors pointed downward and were in a cooler stream of air resulting from the entrainment of very cold air at floor level. It seems that the bottom of the zeolite tank was exposed to 105-110°C air rather than 150°C air as planned. This supposition is supported by the temperature measued by thermistor 15, which was located at the bottom of the zeolite tank. This thermistor essentially summarizes the behavior of the large-scale unit when externally heated. In essence, it's necessary to heat the entire bed above 100°C before water can be driven off. As expected, it was not until the final 2 hours or so of heating that the temperature of the entire unit exceeded 100°C and that water was driven off. By this time both fuel and operator were exhausted and the run was terminated with only 1kg of water collected. Had the entire bed been dehydrated as planned, about 150 kg (350 Ibs) of water would have been liberated. Quite simply, the large unit could not be heated hot enough to store -19- significant quantities of heat. Thus, from the standpoint of energy storage the test was a failure, but the test yielded useful data for the analysis of the performance and for redesign. Theoretical Temperature Distribution. The theoretical temperature distribution for a uniform tank of zeolites heated externally is shown in Appendix H. and is compared with the observed temperature values in Appendix I. The theoretical temperatures were calcu@Jted from the measured thermal conductivity, measured density, known values of the heat capacity and known temperatures and heat-transfer coefficients for hot air. These were used to solve for the temperature distribution at fixed distances within the finite cylindrical tank using Heisler Chart solutions to the appropriate heat-flow equations. It was not possible by this means to take into account the copper heat exchanger which requires a much more complex analysis. The predicted temperatures are below the expected observed temperatures. For those thermistors located in the middle and outer bottom part of the tank (thermistors 6-13), there is reasonably good agreement between predicted temperatures and observed temperatures. Deviations of thermistors 1-5 are from predicted values discussed above. Smal] Unit Four separate tests were carried out with the small unit. Zeolites 5A, TAC1010A(Anaconda Co. clinoptilolite) and Alaska mordenite were dehydrated at 300°C overnite and then rehydrated. Mordenite was also dehydrated at 150°C for 12 hours and then rehydrated. The temperature behavior during rehydration is shown in Appendix J. Looking first at the results of rehydration of mordenite dehydrated at 150°C, no energy was stored. The bed was rehydrated while the zeolite was at 50°C. Addition of 1,100 ml of 25°C water initially cooled the bed to about 37°C after which it slowly reheated to an average temperature of 50°C, the same as the initial temperature. Thus, the heat of hydration was equal to the heat required to heat the added water to the initial temperature of the zeolite bed and no net energy storage was -20- achieved. This test points out several things. The different temperatures recorded by the different thermistors are a result of uneven rehydration of the zeolite bed. This problem is evident in all four tests. Secondly, even though the zeolites near one thermistor were thoroughly irrigated, only a small temperature rise was noted. This suggests that temperatures much greater than 150°C are needed to activate the zeolite completely. Furthermore, the water driven off at low temperatures is as not tightly bound as that liberated at higher temperatures. Thus, the quantity of energy released per g water added is less for mordenite activated at 150°C than for that activated at 300°C. This observation agrees with theoretical considerations and with data reported by Gopal et al. (1982). The rehydration behavior of both TAC 1010A and 5A was like that for mordenite activated at 150°C. Rehydration began when the bed was at 50°C and was accompanied by an initial cooling when the 25°C water was added, followed by 7° to 12° temperature increases. Nonuniform rehydration was evident from the nonuniformity of temperature recorded by the different thermistors. When the unit was opened for inspection following rehydration, large portions of the zeolite bed were still unhydrated. This was espcially true for the 5A which was extremely fine grained having been prepared for detergent manufacture. The TAC1010A was also finer grained than the mordenite, having a particle size between 0.5 and 0.25 mm. It is clear that the more coarse the zeolite is, the more rapid and uniform the hydration and dehydration processes, The rehydration of mordenite activated at 300°C was most encouraging. During activation, 2,607 g H0 were liberated on heating overnight at 300°C, for the expenditure of 9.5kwh. After the unit was cooled to 50°C, rehydration was begun. The temperature of all thermistors climbed immediately. Two of the thermistors showed temperature increase of 36°C ( to 86°C), followed by a slow decline in temperature. The third thermistor slowly increased in temperature to 67°C. Again the uneven hydration behavior is evident in the -21- difference in temperature among the three thermistors. When the unit was subsequently opened, about 1/4 of the zeolite bed was unhydrated. The eneray stored on the different zeolites is summarized in Table 7. In this table, the temperature increase on hydration was calculated from the average measured initial temperature, the mass and temperature of the water the known mass and heat capacities of the zeolites, water and aluminum tank. This temperature change is the difference between the average maximum observed temperature upon hydration and the temperature of mixing calculated from the temperature of the water and the mass of the warm zeolite and aluminum tank. The energy stored by the zeolite unit was calculated from the known heat capacities of the different materials and the calculated temperature increase upon hydration. The results of the small-scale unit experiments point out needed modifications for subsequent work. First, the hydrator needs to be redesigned and tested. Laboratory studies are needed to determine the enthalpies of hydration for the different zeolites activated at different temperatures. The small unit should be redone with the heating unit and thermistors entering through the base rather than being suspended from the lid. This would make filling the unit much easier. More and better thermistors should be distributed throughout the small unit so that the temperature distribution can be mapped. The rehydration behavicr of different zeolite size-fractions should be measured to determine optimum performance. Also, the minimum energy input needed to achieve optimal ‘energy storage must be determined. Finally, the unit should be tested with zeolites from the Iliamna Lake deposits, which must be sampled in bulk. DISCUSSION The results of hydration and dehydration measurements, enthalpy determinations and determination of thermal conductivity can be scaled ~22- from the very small samples on which these properties were measured to the large quantities of zeolites present in a large-scale energy storage unit. We thus are confident that the Iliamna Lake zeolites studied here have excellent potential for use in energy-storage units. Furthermore, using the data we have obtained we see that straightforward heat-flow analysis provides a useful first look at the thermal behavior of possible energy-unit designs. A major goal of this study was to evaluate various Alaskan zeolites for use in energy storage. The Alaskan zeolites appear to be comparable in their properties to the commercially available natural zeolites from the conterminous United States as exemplified by the clinoptilolite TAC1O10A. None of the natural zeolites are capable of storing as much water as the synthetic zeolites 5A or 13X. These zeolites, however, cannot be as densely packed in a thermal unit and, most important, they are much more expensive than natural zeolites. The approximate cost of zeolite 5A is $0.45/1b. This preparation is too fine grained for use in energy storage and the material must be pelletized for such use. Pelletization will increase the cost of the synthetic zeolite 2 to 4 times. Thus, the expected cost of a pelletized synthetic zeolite is probably about $2.00/1b or $4,000/ton. The current price for natural clinoptilolite at Barstow, California ranges from $140-$180/ton depending on particle size (Phelps-Dodge Corp. quotation). Shipping costs are in addition to these costs. The laboratory properties of the Iliamna Lake zeolites are such that these zeolites appear very promising for use in energy storage. As discussed previously, these deposits are readily accessible. We think that clinoptilolite and mordenite can be produced from these deposits, ground, sized and delivered to Anchorage for under $200/ton. Based on the results of this work, can zeolites be used for energy storage in Alaska? In our opinion, the answer is an emphatic yes. _The major factor in their use is the method chosen for heating the zeolite bed. We think that this can be done most efficiently by heating the bed internally with electric heating elements. This method would be most -23- useful for heat storage from off-peak electric power generation. Large- scale units such as that described here could be used for space heating and drying applications. Probably the mest exciting use of zeolites is in small electric radiators for home heating. Recently, Shaw (1983) described a Telefunken heat-storage radiator for home use that stores sensible heat in magnesite bricks. The same concept could be used, substituting our small-scale zeolite energy unit for the magnesite bricks. Such a unit would have the advantage of providing permanent, quickly recoverable storage of about 15% of the total energy input. We think that there is a fine opportunity here for the energy entrepreneur. We conclude that even though we were unsuccessful in building a functioning large-scale energy storage unit, our work provides data that will help make the construction of such a unit possible. Acknowledgements This work was supported by an Alaska Energy Center grant No.AEC 81-005-2, subsequently administered by the Alaska Division of Energy and Power Development. We thank them for their interest and assistance in seeing this project through. We thank T. Neil Davis for his assistance early on in securing funding for this study. We thank Richard Seifert for his support and interest in this work. We are indebted to John Zarling and Ronald Johnson for their helpful discussion of heat-flow calculations. We thank Huan Luong, SylviatLane and Cathy Eagan for their help in preparing the zeolites used and in construction of the energy unit. We particularly thank Robert Geiman of the UAF Library and Katherine Jensen of UAF KUAC-Tv for their willingness to share their facilities and for their forebearance. They truly "let a camel into their tent". -24- REFERENCES Boles, J.R. (1977a) Zeolites in deep-sea sediments: In, Mumpton, F.A., Ed., Mineralogy and Geology of Natural Zeolites, Min. Soc. Am. Short Course Notes, Vol. 4, 132-164. Boles, J.R. (1977b) Zeolites in low-grade metamorphic rocks, In, Mumpton, F.A., Ed., Mineralogy and Geology of Natural Zeolites, Min. Soc. Am. Short Course Notes, Vol. 4, 103-132. Breck, D.W. (1974) Zeolite Molecular Sieves: Structure, Chemistry and Use. Wiley and Sons, NY, 771 pp. Crosby,E.J. (1961) Experiments in transport phenomena: John Wiley and Sons, N.Y.3 190 p. Dudley, J.S., and Ghent, E.D. (1980) Zeolite alteration of the Howson facies volcamics (Jurassic), British Columbia, Canada: In, Rees, L.V.C., Ed., Proceedings of 5th International Conference on Zeolites; Heyden Press, London, 129-138. Eyde, T.H. and D.T, Eyde (1982) Twenty years of natural zeolite production in the United States: Abstracts, 1st International Society of Mining Engineers of AIME, Fall Meeting, Honolulu, Hawaii, Sept.4-9, 1982. Gopal,R.,B.R. Hollebone,C.H. Langford, and R.A. Shigeishi (1982) The rates of solar energy storage and retrieval in a zeolite-water system: Solar Energy cu28(5),p.421-424. Hawkins, D.B. (1976) Commercial grade mordenite deposits of the Horn Mountains, south central Alaska: Alaska Div. of Geol. and Geophys. Surveys, Special Report 11, pp. 39. Hawkins, D.B. (1981) Kinetics of glass dissolution and zeolite -25- formation under hydrothermal conditions: Clays and Clay Minerals, 29, (5), 331-340. Hawkins ,D.B. (1983) Occurrence and availabilty of natural zeolites: in Pond, W.E. and F.A. Mumpton ed. Proceedings of Zeoagriculture Symposium, Westview Press, (in press). Hay, R.L. (1977) Geology of zeolites in sedimentary rocks: In, Mumpton, F.A., Ed., Mineralogy and Geology of Natural Zeolites, Min. Soc. Am. Short Course Notes, Vol. 4, 53-63. Hay, R.L. (1978) Geologic occurrences of zeolites: In, Sand, L.B., and Mumpton, F.A., Eds., Natural Zeolites: Occurrence, Properties, Use; Pergamon Press, Elmsford, NY, 135-145. lijima, A. (1971) Composition and origin of clinoptilolite in the Nakanosawa tuff of Rumoi, Hokkaido: In Gould, R.F., Ed., Molecular Sieve Zeolites-1: Am. Chem. Soc., Advances in Chemistry Series 101, 540-547. Tijima, A. (1978) Geological occurrences of zeolites in marine environments: In, Sand, L.B., and Mumpton, F.A., Eds., Natural Zeolites: Occurrence, Properties, Use; Pergamon Press, Elmsford, NY, 175-198. lijima, A. (1980) Geology of natural zeolites and zeolitic rocks: In, Rees, L.V.C., Ed., Proceedings of 5th’ International Conference on Zeolites; Heyden Press, London, 103-118. lijima, A. and Ohwa, I. (1980) Zeolitic burial diagenesis in Creta-tertiary geosynclinal deposits of central Hokkaido, Japan: In, Rees, L.V.C., Ed., Proceedings of 5th International Conference on Zeolites; Heyden Press, London, 139-148. lijima, A. and Utada, M. (1971) Present-day zeolitic diagenesis of the Neogene geosyncline deposits of the Niigata oil field, Japan: In, -26- Gould, R.F., Ed., Molecular Sieve Zeolites-1: Am. Chem. Soc., Advances in Chemistry Series 101, 548-555. Istrate, G. (1980) Zeolites of Romania: their nature and occurrences: In, Rees, L.V.C., Ed., Proceedings of 5th International Conference on Zeolites; Heyden Press, London, 149-154, Kristmannsdottir, H. and Tomasson, J. (1978) Zeolite zones in geothermal areas in Iceland: In, Sand, L.B. and Mumpton, F.A., Eds., Natural Zeolites: Occurrence, Properties, Use; Pergamon Press, Elmsford, N.Y., 277-285. Leonard, D.W. (1982) Marketing of natural zeolites: Abstract, Ist International Soc. of Mining Engineers of AIME, Fall Meeting, Honolulu, Hawaii, Sept. 4-9, 1982. Madonna, J.A. (1977) Zeolite deposits of possible economic significance on the northern Alaska peninsula: Alaska Div.of Geol. and Geophys. Surveys, Open File Report 87, 25pp. Maltoni, C., Minardi, F., Morisi, L. (1982) Pleural mesotheliomas in Sparague-Dawley rats by erionite: first experimental evidence. Environ. Res., 29(1), 238-44. Minato, H. and Utada, M. (1971) Clinoptilolite from Japan: In, Gould, R.F., Ed., Molecular Sieve Zeolites-1: Am. Chem. Soc., Advances in Chemistry Series 101, 535-539. ’ Mumpton, F.A. (1981a) Zeolites and mesothelioma: In, Sersale, R. et al., Eds., Recent Progress Reports and Discussion: 5th International Conference on Zeolites: Giannini, Naples, Italy, 261-285. Mumpton, F.A. (1981b) Utilization of zeolites in agriculture: In, Background Papers for Innovative Biological Technologies for Lesser Developed Countries, An Office of Technology Assessment -27- Workshop, November 24-25, 1980; Report for the Committee on Foreign Affairs, U.S. House of Representatives, September, 1981. Rohl, A.N., Langer, A.M., Moncure, G., Selikoff, I.J. and Fischbein, A. (1982) Endemic pleural disease associated with exposure to mixed fibrous dust in Turkey: Science, 216, 518-520, Sameshima, T. (1978) Zeolites in tuff beds of the Miocene Waitemata Group, Auckland Province, New Zealand: In Sand, L.B. and Mumpton, F.A., Eds., Natural Zeolites, Occurrence, Properties, Use: Pergamon Press, Elmsford, NY, 3, 09-318. Scherillo, A. and Porcelli, C. (1981) Field guide to the tuff deposits of the Neapolitan district: In Sersale, R. et al., Eds., Recent Progress Reports and Discussion: 5th International Conference on Zeolites: Giannini, Naples, Italy, 291-300. Scott ,David(1980) Double-duty heat pump stores chemical heat too: Popular Science. Sersale, R. (1978) Occurrences and uses of zeolites in Italy: In, Sand, L.B. and Mumpton, F.A., Eds., Natural Zeolites, Occurrence, Properties, Use: Pergamon Press, Elmsford, NY, 285-302. Shaw, A.L. (1983) Off peak elelctric heating: The Northern Engineer, 14(4) ,p.30-34. Sheppard, R.A. (1971) Zeolites in sedimentary deposits of the United States-a review: In, Gould, R.F., Ed., Molecular Sieve Zeolites-1: Am. Chem. Soc., Advances in Chemistry Series 101, 279-310. Sheppard, R.A. (1973) Zeolites in sedimentary rocks: U.S. Geol. Surv. Prof. Paper 820, 689-695. ‘ -28- Sheppard, R.A., Gude, A.J., 3rd, and Edson, G.M. (1978) Bowie zeolite deposit, Cochise and Graham Counties, Arizona: In, Sand, L.B. and Mumpton, F.A., Eds., Natural Zeolites, Occurrence, Properties, Use: Pergamon Press, Elmsford, NY, 319-328. Sheppard, R.A. and Gude, A.J., 3d (1982) Mineralogy, chemistry, gas adsorption, and NH4”~exchange capacity for selected zeolitic tuffs from the western United States: U.S. Geol. Survey Open-File Report 82-969. Shigeishi,R.A.,C.H. Langford and B.R. Hollebone(1979) Solar energy storage using chemical potential changes associated with drying of zeolites. Solar Energy 23, p489-495. Surdam, R.C. (1977) Zeolites in closed hydrologic systems: In, Mumpton, F.A., Ed., Mineralogy and Geology of Natural Zeolites, Min. Soc. Am., Short Course Notes, Vol. 4, 65-92. Surdam, R.C. and Sheppard, R.A. (1978) Zeolites in saline, alkaline-lake deposits: In, Sand, L.B. and Mumpton, F.A., Eds., Natural Zeolites, Occurrence, Properties, Use: Pergamon Press, Elmsford, NY, 145-175. Suzuki, Y. (1982) Carcinogenic and fibrogenic effects of zeolites; preliminary observations: Environ. Res. 27,(2), 433-445, Tchernev,D.I. (1978) Solar energy applications of natural zeolites. in Sand,L.B. and F.A. Mumpton ed. Natural Zeolites, occurrence, properties ,use. Pergamon Press, p479-486. -29- Table 1. Main compositional Features of Zeolites found in Sedimentary Rocks (Hay, 1977). Zeolite si/Al+fe*? Dominant Cations Clinoptilolite 4.0-5.1 K Na Mordenite 4,3-5.3 Na K Heulandite 2.9-4.0 Ca, Na Erionite 3.0-3.6 Na, K Chabazite 1.7-3.8 Ca, Na Phillipsite 1.3-3.4 K, Na, Ca Analcime 1.7-2.9 Na Laumontite 2.0 Ca Wairakite 2.0 Ca Natrolite 1.5 Na -30- Table 2, Reported Occurrences of Sedimentary Zeolites (Mumpton, 1981b). Zeolite Mineable Minor Chances for Country Species Deposits Occurrence Deposits EUROPE Belgium Laumontite Xx Poor Bulgaria Clinoptilolite xxx Excellent Mordenite x Excellent Analcime x Poor Czechoslovakia Clinoptilolite x Good Denmark Clinoptilolite x Poor Finland Laumontite x Poor France Clinoptilolite XXX Good Germany Chabazite XX Good Phillipsite XX Good Analcime XX Poor Great Britain Analcime x Poor Clinoptilolite x Poor Laumontite x Poor Hungary Clinoptilolite xx Excellent Mordenite x Excellent Italy Chabazite XXX Excellent Phillipsite XXX Excellent Analcime x Good Poland Clinoptilolite xx Excellent Romania Clinoptilolite xx Excellent Soviet Union Clinoptilolite xxx Excellent Mordenite xXx Excellent Chabazite x Good Analcime X Good Laumontite x Good Spain Clinoptilolite X Good Mordenite x Good Switzerland Clinoptilolite x Poor Laumontite XX Poor Turkey Clinoptilolite xx Excellent -31- Table 2. (Continued) Zeolite Mineable Minor Chances for Country Species Deposits Occurrence Deposits Erionite XX Excellent Chabazite XX Excellent Analcime x Excellent Yugoslavia Clinoptilolite xxx Excellent Analcime x Good Mordenite x Excellent Erionite Xx Good AFRICA Angola Clinoptilolite x Good Botswana Clinoptilolite x Good Congo Analcime x Good Egypt Heulandite Xx Good Kenya Phillipsite x Excellent Erionite x Excellent Northwest Africa Analcime x Good Mordenite x Good Clinoptilolite x Excellent Republic of South Africa Analcime Xx Poor Clinoptilolite xx Excellent Tanzania Erionite x Excellent Chabazite x Excellent Phillipsite x Excellent Analcime x Excellent Clinoptilolite x Excellent ASIA Iran Clinoptilolite x Excellent Israel Clinoptilolite XX Excellent Pakistan Analcime Xx Good Australia Clinoptilolite x Good Analcime x Good China Clinoptilolite xx Excellent -32- Table 2. (Continued) Zeolite Mineable Minor Chances for Country Species Deposits Occurrence Deposits Formosa Laumontite x Poor Analcime x Good Japan Clinoptilolite xxx Excellent Mordenite XXX Excellent Analcime x Poor Laumontite x Poor Wairakite x Poor Korea Clinoptilolite xx Excellent New Zealand Analcime x Good Clinoptilolite xx Good Mordenite x Excellent Laumontite x Good Erionite x Good Oceania Laumontite Xx Poor SOUTH AMERICA Argentina Clinoptilolite xx Excellent Analcime Xx Excellent Laumontite x Poor Chile Clinoptilolite x Excellent NORTH AMERICA (exclusive of the United States) Canada Laumontite x Poor Clinoptilolite Xx Good Cuba Clinoptilolite +: xx Excellent Mordenite x Excellent Guatamala Clinoptilolite x Excellent Mexico Clinoptilolite xx Excellent Mordenite XX Excellent Analcime x Good Erionite x Excellent Phillipsite x Excellent Panama Clinoptilolite x Excellent West Indies Wairakite x Poor Clinoptilolite x Excellent -33- Table 2. (Continued) Zeolite Mineable Minor Chances for Country Species Deposits Occurrence Deposits ANTARCTICA Antarctica Laumontite x Poor Phillipsite x Poor -34- Table 3. (Mumpton, 1981b). Countries Currently Engaged in Zeolite Mining Country Mineral Mines Remarks United States Clinoptilolite 12 Many more available Chabazite 4 Single deposit, 4 companies Erionite 2 Mordenite 1 Mexico Mordenite/ Clinoptilolite 1 Cuba Clinoptilolite 1 Japan Clinoptilolite 8 Estimated Mordenite 5 Estimated Korea Clinoptilolite 2 Bulgaria Clinoptilolite 1 Hungary Clinoptilolite 1 Mordenite 1 Estimated Soviet Union Clinoptilolite 3 Estimated Mordenite 1 Estimated Yugoslavia Clinoptilolite 2 Several more available South Africa Clinoptilolite 1 Italy Chabazite/ Phillipsite Numerous, used for construction Germany Chabzite/ Phillipsite Several, used for construction Table 4. United States Zeolite Property Holders! (Table 20, Mumpton, 1981b). Organization Anaconda Company Colorado Lien Company Double Eagle Petroleum and Mining Company Forminco Harris & Western Company Ladd Mountain Mining Co. Leonard Resources Letcher Associates Minerals Research Minobras, Inc. Mobil Oil Corp. Monolith Portland Cement Company NL Industries Norton Company NRG Company Occidental Minerals Corp. Rocky Mountain Energy Company Zeolite Species” Clinoptilolite, Erionite Chabazite/Erionite, Clino- ptilolite, Chabazite, Mordenite, Phillipsite. Clinoptilolite Clinoptilolite CTinoptilolite Clinoptilolite Clinoptilolite/Mordenite Erionite/Clinoptilolite Clinoptilolite Clinoptilolite Phillipsite Erionite Erionite Clinoptilolite Clinoptilolite Chabazite/Erionite errierite Chabazite/Erionite Clinoptilolite, Clinoptilolite, Erionite Clinoptilolite -36- Table 4. (Continued) Organization Zeolite Species” Union Carbide Chabazite/Erionite, Corporation Mordenite, Erionite U.S. Energy Clinoptilolite Corporation W.R. Grace Chabazite/Erionite Ferreirite HS : : Because of present depressed economy many of the zeolite suppliers listed here have either gone out of business or have greatly curtailed their operations. At present, the only major supplier of natural zeolites is the Phelps Dodge Corporation which has obtained many of the Anaconda Company and Occidental Minerals Corpation holdinas. 2Underl ined type = working mines; non-underlined = prospects. -37- Table 7. Summary of Thermal Behavior, Small Energy Storage Unit Activation Energy %Max Energy Material Temperature T hyd. Stored Energy Input fordenite 150°C 0 0 0 - nd. Mordenite 300 38 421Kcal 76 8160 Kcal Clinoptilolite 300 12 so 30 2150 (TAC1010A) 5A 300 6 38 9 4300 Table 6. Measured Enthalpies of Hydration for Selected Zeolite Samples Sample Enthalpy (kcal/kg Zeolite) Mordenite 23 (Horn Mountain) Clinoptilolite 23 (TAC 1010A) Mordenite 15 (Iliamna-23) Mordenite 20 (Iliamna-15) Heulandite 16 (Iliamna-13) 5A 42 13X 200! 1 Literature value (Tchernov 1978) on 12 kcal/mole H 20 and 30% H 90 by weight on 13X. -38- Table 5, X-ray Diffraction Analyses of Zeolitized Tuffs Ileamna Sample Number WOON DOP WMHH 1 Lake. Mineraloay@ Clinoptilolite,quartz, plagioclase quartz ,plagioclase,mica heulandite,smectite,quartz,plagioclase tT u uw nu mordenite, " " " tT uW " “ heulandite, " " " quartz, plagioclase ,heulandite,smectite quartz plagioclase mordenite,quartz,plagioclase quartz ,plagioclase,smectite ,heulandite heulandite,quartz,plagioclase ' " 7 ssmectite clinoptilolite," " quartz ,plagioclase,clinoptilolite u u plagioclase ,quartz mordenite,quartz,plaqgioclase TT u clinoptilolite,quartz,plagioclase Isoe Figure 1 for sample locations. 27e0lites are underlined, most abundant phase listed first 3clinoptilolite was distinguished from heulandite on basis of heating tests. (See Hawkins, 1976). -39- Appendix Appendix Appendix Appendix Appendix Appendix Appendix Appendix Appendix Appendix TABLE OF APPENDICES Zeolite locality map, Iliamna Lake area. Thermal gravimetric analysis of selected zeolite samples. Dehydration of mordenite, clinoptilolite(TAC1010A) and 5A at different times and temperatures. Grain-size distribution of mordenite used in the large-and small -scale energy storage units. Diagram of large-scale energy storage unit. Diagram of small-scale energystorage unit. Observed temperatures of different thermistors during the 43 hour heating period for the large-scale energy -storage unit. Theoretical temperature contours for large-scale energy storage unit at several times. Predicted versus observed temperatures for thermistors 1 through 15 of the large-scale energy storage unit. Observed rehydration behavior of zeolites in the small-scale energy- storage unit. Appendix A. Zeolite locality map, Iliamna Lake area. Re IRS US / Appendix B. Thermal gravimetric analysis of selected zeolite samples. % WT.LOSS signe tyrutie Oe SAREE AREER ES Te ni examen teeter atc ieee T.G.A. ANALYSIS -TAC 181@A + . . + + + + + + + + + + +++ + —- + — + Lr) Cd + wo co = o In a a a Mu ou TEMP-C 378 % WT. LOSS Ming RITZ Deyo Keer Soo SE ete mA eet ae state 16 13 1G Ae ANALYSIS MORDENITE 1g +++ ' TEMP-C + + + + + + a + + + + + + +t ou +r wo oO oo n wb on a ow cu 378 - 14 T.GiA. ANALYSIS ILIAMNA-H-10-91 + | + + + + + _ + | + + + | + + + + + + + + + + + + ' 7 Sg cw t © . = co s © o 4 a rH TEMP C a78 + T.G.A. ANALYSIS I[LIAMNA-H23-8 1 13 + ] + + + 14 { + + + | + N > | 7 oP + 16D) © t + 4 7 + ke 5 + = = + Melictanteigeyictess se: me ues wales Waddietecic ct aon ikea a Pee Bi ont secrets eb 2 + + -l1 + +— - t —+ t H + + g od vr wo ao == oO n ws nD ~ wl cu TEMP-C 37a + % WT.LOSS IIMs 9 A es I a ae 16 oO) ANALYSIS ILIAMNA-H13-81 4 + + -+ + i + + | + a | + | + + t + + y cu t wo o = oO In a a — a cu TEMP-C 37a + T.G.A. ANALYSIS -ZEOLITE 5A 24 + | +e + ~ + 19 + + + . T + N 14 + + i oS } * — + = 3 + + = + Pee Brat 8 ts ett | . + pegs 4 . + + -l +t + + + + + + + + 4 gS od +r wo a gy = co n w na ~ ~ a ou om TEMP-C AGM att So % WT.LOSS 29 23 1? 11 1g T.G.A, ANALYSIS-ZEOLITE 13x + + + + + + + + + —t + t + + 4 Od + wo co oO nm w on a a cu TEMP-C 278 Appendix C. Dehydration of mordenite,clinoptilolite(TAC1010A) and 5A at different times and temperatures. WT.LOSS o MORDENITE DEHYDRATION 158-368 ¢ 300 —- + > 250 “+ ~ 200 —+ — 150 +“ ~ — + + + + + + n co co . co HOURS WT.LOSS HOURS 162 7 13a WT.LOSS 19 VA DEHYDRATION 158-366 C 300 —_+— — —- 250 a oF +r 25f 200, T + + | : *150 | g fos) lo + cu 7 _ +r i a HOURS 13a i Appendix D. Grain-size distribution of mordenite used in the large-and small- scale energy storage units. PERCENT bee — ro fu NI To ™M Mw +$++-++- + +4 >4MM Sy L <4MM> 2MM a Al <2MM> 1MM a - uw : HH <1MM>.5MM i rm <.5MM>.25MM <.25MM>. 125MM <.125MM>.@625MM <.@625MM tiot CUM. PERCENT 166+ 45.2% PERCENT m~ Qo @ t—t pacer igee >4MM MM> 1MM . 125MM <4MM>2MM <2 <1MM>.5MM » <.5MM>.25MM <.@625MM <.25MM> . 125MM>.@625MM < Appendix E. Diagram of large-scale energy storage unit. Zeolite Energy Storage Unit Duct Fram Exhaust Duct Dehydrator Valve Heat Exchanger Outlet Hydrator Valve Thermistor Fiber Wires Glass Heat Exchanger Hydrator Tube Thermistor Heat Exchanger Inlet hs 6 Feet >| iop view Duct Fan Hydrator Valve Thermijstor Wire Conduit Fiber. Th ist Glass ermistor Exhaust Duct Dehydrator Valve Heat Exchanger Outlet Heat Exchanger pe e--~—~——-— -- - ~~ Inlet Appendix F. Diagram of small-scale energy storage unit. Bench =-Scale Element Hydrator Thermistor Heating Dehydrator Thermjstor Valve i Bolt Wires . r a Ai oe KK #8 Panne c Ae ro < : = mi Le a K ay ™| 7 AL] o tl il ae a o 5 y Soe cy, 2 3 N - Hydrator Valve Trash Ca Fiber Glass. Autoclave ~ °o o las Appendix G. Observed temperatures of different thermistors during the 43 hour heating period for the large-scale energy-storage unit. 7a twerge yore WR ER TO Rs y ro€ 4 TEMPERATURE-deg C rho tiititirdi dy thotiitis | thot tidbits a 66 l2 18 24 34 36 42 48 TIME — HOURS ~THERMISTOR 1 -TEMPERATURE-deqg C rbhok rboitiiti tists t l2 18 a 6 TIME moititiitiitiibtiiti ty 42. «48 a4 34 36 — HOURS THERMISTOR @ TEMPERATURE-deq C thitdiitiitibr ttt hy 8 6 le 18 et 3G 36 42 48 TIME —- HOURS THERMISTOR 3 - 1668 C -TEMPERATURE-deg C bititiils 6 l iil 2 tT thitiititiitiitiitiity 18 e4 34 36 4 IME —- HOURS THERMISTOR 4 if iil 2 uty 48 oO TEMPERATURE-deq C thobototiboibitibibibi bbb bt a 6 le 18 24 3H 36 42 48 TIME -— HOURS THERMISTOR 9 1a@ Cc TEMPERATURE-deg C thiitvibitiitiditis tity a 6 l2 18 24 36 36 42 48 TIME - HOURS THERMIS TOR 6 TEMPERATURE-deg Cc TIME - THERMISTOR 7 botibitetib titi titi lotiitiitiy 6 le 18 et 34 36 42 48 HOURS el Oo TEMPERATURE-deg C otiitiits 6 l rhortiitiitis tii] 2 18 24 ptotiitibiititi diy 3G 36 42 43 TIME - HOURS FHERMISTOR 8 - 188 TEMPERATURE-deq C titi d titi t td 8 6 l2 18 24 34 36 42 46 TIME — HOURS THERMISTOR 3G TEMPERATURE-deg C thotiitiitiitiy bosdis titi ititiitiiti tid tay G 6 l2 18 24 3G 36 42 48 TIME —- HOURS THERMISTOR 18 TEMPERATURE-deq C besdiitii dest d orbs te debt dd dy G 6 le 18 24 34 36 42 48 Ee all LU RS THERMISTOR 11 Ge fea} oO TEMPERATURE-deq C bottititirhitiy rhoidiils G 6 le 18 24 346 3 TIME -— HOURS THERMISTOR 12 thiitiititbitiy 6 42 48 TEMPERATURE-deg C thotiitistertivtiidii tii dist a 6 l2 18 24 photitibitili dy, 3G 36 42 48 TIME - HOURS THERMISTOR 13 TEMPERATURE-deg C htt titty uh Hote tita a 6 18 24 36 36 TIME - HOURS THERMISTOR 14 TEMPERATURE-deg C rhotiitiititiils 8 6 ke 1 l | ul 8 24 mtitils 34 36 TIME -— HOURS THERMISTOR 15 thioitiitiitiy 42. 48 TEMPERATURE-deg C rhortiidiitiediitiitortis tis 8 6 le 18 24 ritiidiy | ch 38 36 42 48 TIME —- HOURS THERMISTOR 16 TEMPERATURE-deq C Hiitititititititit bbb dy 6 le 18 24 34 36 42 48 TIME -— HOURS . THERMISTOR 1? TEMPERATURE-deg C tbrtdiitibititiitiyt a 6 le 18 TIME THERMISTOR rtitiitititititiitis ty 24 346 36 42 48 - HOURS TEMPERATURE-deg C thiitirbisbirtititiel botiitiil 6 l2 18 24 34 36 TIME — HOURS THERMISTOR 19 util 42 itis 48 TEMPERATURE-deq C a 6 le 18 24 3G 36 TIME — HOURS THERMISTOR 24 42 48 - 166 ¢ TEMPERATURE-deq C Jslula bostoitiibititti ditt dy a le 18 24 34 36 42 48 TIME — HOURS THERMISTOR 21 io) oO TEMPERATURE-deg C THERMISTOR 28 & e oO TEMPERATURE-deg C Lotivir sl Hs Phe Ghibli a 6 l2 18 24 3G 36 42 48 TIME - HOURS THERMISTOR 1 eg - 168 O cC TEMPERATURE-deg 348 36 TIME -— HOURS THERMISTOR 364 42 AREA HAF TTC " Appendix H. Theoretical temperature contours for large- scale energy storage unit at several times. one [ +16 +14 +15 156 146 136 N-S TRANSVERSE SECTION. WITH RADIAL AND AXIAL DISTANCES, THERMISTOR LOCATIONS, AND TEMPERATURE CONTOUR VALUES SHOWN E-W TRANSVERSE SECTION, WITH RADIAL AND AXIAL DISTANCES, THEORETICAL TEMPERATURES AND THEORETICAL TEMPERATURE CONTOUR VALUES SHOWN. AFTER 6 HOURS E-hW TRANSVERSE SECTION, WITH RADIAL AND AXIAL DISTANCES, THEORETICAL TEMPERATURES AND THEORETICAL TEMPERATURE CONTOUR VALUES SHOWN AFTER 48 HOURS 146 156 40 il CROSS SECTION, WITH RADIAL DISTANCES THERMISTOR LOCATIONS, AND TEMPERATURE CONTOUR YALUES SHOWN x st esoeanecesosscnasese Roane secs Pe eaeeas eats eae Rae ae Se SE Saeeseeocosesessoancoese rococo sees Kora ococacoesnae nese sear se se ese Pee fh ' MIDDLE cross SECTION - THERMISTORS 6 To 14 wor RUN #1 AFTER 6 HOURS Appendix I. Predicted versus observed temperatures for thermistors 1 through 15 of the large-scale energy-storage unit. z a i oO Temperature Cc TOBS VERSUS TPRED - 6 HOURS Thermistor | 13 4 15 TOBS VERSUS TPRED- 24 HOURS eg 151 1 iat x J 2 4 = le2 oe S| f o | Ty ee - a | \e- eee eee ~ | mot | - Thermistor 161 151 UO ° 2 148 = ~ © = o a E | 130 Lage TOBS VERSUS TPRD - 43 HOURS - —+ — —— + + + — _ 4 no ~ n — ~ wn Thermistor Appendix J. Observed rehydration behavior of zeolites in the small-scale energy-storage unit. TEMP 1] Pt on wo s+ 46 29 MORDENITE 158 R EHYDRAT ION 34 78 TIME 122 + 166 + 218 + TEMP TAC 1618A REHYDRATION eeeatgettga tte tee ttt tteet teeta + + + tet eetetgtggggeye gg ++ TH+ tttte te gggay 66 142 218 + 2eo4¢ 37g + TIME ZEOLITE SA REHYDRATION 61 7 Mw +t treet eetrer ee tere ere reget + + + Sf f+ He ae + + + + We Se + “ il a ao +, = T | | uu + bE + Sore irae Pec Sra cei | 39 ~ — + + + + + + —+ S cu + w oO — + n + n | “ “4 TIME TEMP 1 7g el 64 56 49 nl t MORDENITE 386 REHYDRATION -14 + + + + + + + + + + +e + + + + + i) ¢ + + + + + + + + + + + + 7 4 + + t+ + + — + —+ +— +- oe — - co ow wo gS m i rat wo “ _ _ Ww TIME