Utility waste


The outer layer of the onion diagram in Fig. 1.6 (the utility system) produces utility waste. The utility waste is composed of the products of fuel combustion, waste from the production of boiler feedwater for steam generation, etc. However, the design of the utility system is closely tied together with the design of the heat exchanger network. Hence, in practice, we should consider the two outer layers as being the source of utility waste.  [c.274]

The principal sources of utility waste are associated with hot utilities (including cogeneration) and cold utilities. Furnaces, steam boilers, gas turbines, and diesel engines all produce waste as gaseous c bustion products. These combustion products contain carbon  [c.274]

Let us look at how waste from each of these sources might be reduced before considering treatment methods in the next chapter. Since one of the themes running throughout the design philosophy presented here has been waste minimization through high process yields, elimination of extraneous materials, etc., much of the discussion to follow will summarize arguments already presented. However, this discussion shall go further and draw together the arguments into an overall philosophy of waste minimization. Since the reactor is at the heart of the process, this is where to start when considering waste minimization. The separation and recycle system comes next, then process operations, and finally, utility waste.  [c.275]

Minimization of Utility Waste  [c.290]

Utility systems as sources of waste. The principal sources of utility waste are associated with hot utilities (including cogeneration systems) and cold utilities. Furnaces, steam boilers, gas turbines, and diesel engines all produce waste from products of combustion. The principal problem here is the emission of carbon dioxide, oxides of sulfur and nitrogen, and particulates (metal oxides, unbumt  [c.290]

Energy efficiency of the process. If the process requires a furnace or steam boiler to provide a hot utility, then any excessive use of the hot utility will produce excessive utility waste through excessive generation of CO2, NO, SO, particulates, etc. Improved heat recovery will reduce the overall demand for utilities and hence reduce utility waste.  [c.291]

Local and global emissions. When considering utility waste, it is tempting to consider only the local emissions from the process and its utility system (Fig. 10.8a). However, this only gives part of the picture. The emissions generated from central power generation are just as much part of the process as those emissions generated on-site (Fig. 10.86). These emissions should be included in the assessment of utility waste. Thus global emissions are defined to be °  [c.291]

This is particularly important when considering the effect that combined heat and power generation (cogeneration) has on utility waste.  [c.291]

Combined heat and power cogeneration). Combined heat and power generation can have a very significant effect on the generation of utility waste. However, great care must be taken to assess the effects on the correct basis.  [c.291]

Assessing only the local efiects of combined heat and power is misleading. Combined heat and power generation increases the local utility emissions because, besides the fuel burnt to supply the heating demand, additional fuel must be burnt to generate the power. It is only when the emissions are viewed on a global basis, and the emissions from central power generation included, that the true picture is obtained. Once these are included, on-site combined heat and power generation can make major reductions in global utility waste. The reason for this is that even the most modem central power stations have a poor efficiency of power generation compared with a combined heat and power generation system. Once the other inefficiencies associated with centralized power generation are taken into account, such as distribution losses, the gap between the efficiency of combined heat and power systems and centralized power generation widens.  [c.292]

Fuel switch. The choice of fuel used in furnaces and steam boilers has a major effect on the gaseous utility waste from products of combustion. For example, a switch from coal to natural gas in a steam boiler can lead to a reduction in carbon dioxide emissions of typically 40 percent for the same heat released. This results from the lower carbon content of natural gas. In addition, it is likely that a switch from coal to natural gas also will lead to a considerable reduction in both SO, and NO, emissions, as we shall discuss later.  [c.293]

Waste from steam systems. If steam is used as a hot utility, then inefficiencies in the steam system itself cause utility waste. Figure 10.9 shows a schematic representation of a steam system. Raw water from a river or other source is fed to the steam system. This is  [c.293]

This make up causes utility waste  [c.294]

The utility system also creates waste through products of combustion from boilers and furnaces and wastewater from water treatment, boiler blowdown, etc. Utility waste minimization is in general terms a question of  [c.297]

In Chap. 10, modification of the process for reducing process waste was considered in detail. It also was concluded that to minimize utility waste, the single most effective measure would be improved heat recovery. The energy-targeting methods presented in Chaps. 6 and 7 maximize heat recovery for a given set of process conditions. However, the process conditions can be changed to improve the heat recovery further.  [c.321]

The ultimate reference in guiding process changes to reduce utility costs and utility waste is the plus/minus principle. However, process changes so identified prompt changes in the capital/energy tradeoff and utility selection. Using the total cost targeting techniques described in Chaps. 6 and 7, it is possible to effectively screen a wide range of options using relatively simple computation. In the next three chapters we shall focus in detail on heat integration of reactors and heat-driven separators.  [c.323]

The structure of the reaction-separation system has now been fixed, and some optimization of the major design variables (reactor conversion, recycle inert concentration, etc.) has been carried out. This optimization has been carried out using only targets for the heat exchanger network and utilities. Minimization of process waste has been considered. Utility waste and cost have been minimized by improving heat integration. Again, the process changes to improve heat integration have been carried out using targets for the heat exchanger network and utilities.  [c.363]

Process changes for improved heat integration. Having minimized process waste, energy costs and utility waste can be reduced further by directing process changes to allow the energy targets to be reduced. The ultimate reference in guiding process changes is the plus/minus principle.  [c.402]

The need to meet environmental regulations can affect processing costs. Undesirable air emissions may have to be eliminated and Hquid effluents and soHd residues treated and disposed of by incineration or/and landfilling. It is possible for biomass conversion processes that utilize waste feedstocks to combine waste disposal and treatment with energy and/or biofuel production so that credits can be taken for negative feedstock costs and tipping or receiving fees.  [c.16]

Refractories made usiag alumiaas are used ia the iroa and steel, chemical and petroleum, ceramics and glass manufacture, minerals processiag (cement, lime, etc), pubHc utilities, waste iaciaeration, and power generation iadustries.  [c.163]

Combined-cycle power plants, typically faciUties that utilize waste heat from a gas turbine cycle or such technology as reciprocating engines to generate steam for use in a second power generation cycle, have become the most efficient and economical means of generating power in many areas of the world (Figs. 12 and 13). The combined-cycle faciUty, based on linking the gas turbine or Brayton cycle and the Rankine cycle, is the most common type.  [c.12]

Absorption chiller units (Fig. 13) need 1.6—1.8 J (0.38—0.43 cal) of waste heat per joule (0.24 cal) of refrigeration. Commercially available LiBr absorption units are suitable for refrigeration down to 4.5°C. For low level waste heat (90—120°C), absorption chillers utilize waste heat as efficientiy as steam turbines using mechanical refrigeration units. Absorption refrigeration using 120°C saturated steam deUvers 4.5°C refrigeration, having an efficiency, with respect to the work potential in the steam of 35%.  [c.92]

As an alternative to raising firing temperature, overall power plant performance can be improved by modifications to the cycle. Combining a land-based simple cycle gas turbine with a steam turbine results in a combined cycle that is superior in performance to a simple gas turbine cycle or a simple cycle steam turbine considered separately. This is due to utilizing waste heat from the gas turbine cycle. By 1999, land-based sample cycle gas turbine efficiencies had improved from 18 percent to more than 42 percent, with the better combined cycles reaching 58 percent, and the ones in development likely to exceed 60 percent. Combined cycle efficiency improvements have followed the general advance in gas turbine technology reflected in the rising inlet temperature trend shown in Figure 3, which, in turn, was made possible by advances in components and materials.  [c.1174]

Product quality specification Contractual agreements Capacity and availability Concurrent operations Monitoring and control Testing metering Standardisation Flaring and venting Waste disposal Utilities systems  [c.279]

Most natural gas (i.e., methane) is still burned to produee energy. However, methane (CH4) should be recognized as a most valuable souree for higher hydrocarbons, because in it nature provides us with the highest possible (4 1) hydrogen-to-carbon ratio. The question is, how ean we utilize methane to obtain higher hydrocarbons and their derivatives from it directly, without wastefully burning it (albeit incompletely) first to synthesize gas (CO and H2) to be used in Fischer-Tropsch chemistry  [c.211]

Biodegradation. The biological mineralization of fixed nitrogen is well studied ammonia is oxidized to nitrite, and nitrite to nitrate, by autotrophic bacteria, and nitrate is reduced to nitrogen by anaerobic bacteria. Urea ia sewage and iadustrial wastes is readily hydrolyzed to ammonia and CO2 by many bacteria, and cyanides and cyanates are used as sole sources of carbon and nitrogen by some organisms. Wastewater treatment faciUties utilize these organisms ia assuting that municipal and iadustrial efflueats meet strict water quaUty standards, but this biological process is outside the scope of this article (see Water, industrial water treatment Water, municipal water treatment). On the other hand, ammonia and nitrate are essential nutrients for plant and bacterial growth, so one option is to use these organisms to take up and use the contaminants.  [c.36]

The ratio of reactants had to be controlled very closely to suppress these impurities. Recovery of the acrylamide product from the acid process was the most expensive and difficult part of the process. Large scale production depended on two different methods. If soHd crystalline monomer was desired, the acrylamide sulfate was neutralized with ammonia to yield ammonium sulfate. The acrylamide crystallized on cooling, leaving ammonium sulfate, which had to be disposed of in some way. The second method of purification involved ion exclusion (68), which utilized a sulfonic acid ion-exchange resin and produced a dilute solution of acrylamide in water. A dilute sulfuric acid waste stream was again produced, and, in either case, the waste stream represented a  [c.134]

Manufacture Various methods for the manufacture of acrylates are summarized in Figure 1, showing thek dependence on specific raw materials. For a route to be commercially attractive, the raw material costs and utilization must be low, plant investment and operating costs not excessive, and waste disposal charges minimal.  [c.151]

Strength of the caustic solution, temperature, contact time, and amount used are the critical parameters used to set optimum refining conditions. The type of oil and its free fatty acid and phosphatide content greatiy influence refining behavior. An oil with a high phosphatide content requires a greater excess of sodium hydroxide than an oil with low phosphatide concentration. Soapstock is a by-product of alkah refining. It is commonly acidified and the fatty acids are utilized for animal feed. Alternatively, the acidified soapstock may be treated to spht fatty acids from residual glyceride and the fatty acids distilled and sold as commercial products. A modification of alkah refining has minimized or eliminated the water stream associated with alkah refining (15). Sihca is utilized with a lower concentration of alkah to refine the oil. Soap is absorbed on the sihca and subsequent bleaching clay rather than being washed out and neutralized. Soap is therefore disposed of as sohd waste along with the bleaching clay and sihca rather than acidified and concentrated to cmde fatty acid.  [c.125]

Generally, for most fermentation processes to yield a good quality product at a competitive price, at least six key criteria must be met. (/) Fermentation is a capital intensive business and investment must be minimised. (2) The raw materials should be as cheap as possible. (J) Only the highest yielding strains should be used. (4) Recovery and purification should be as rapid and as simple as possible. (5) Automation should be employed to minimise labor usage. (6) The process must be designed to minimise waste production and efftciendy use all utilities (26,27).  [c.184]

If the daily rent is corrected by an equipment utilization factor, simple products for which only part of the equipment is used can show a good profit margin without providing a good return for the overall investment in the multipurpose plant. Eor portfoHo optimization, not only the profit margin but also the marginal income per day have to be considered. In other words, marketing has to be given the task of finding substitutes for products that have low equipment utilization, such as A, C, and D in Eigure 3. Pretreatment and disposal of waste effluents substantially increase the cost of a fine chemical. Up to 50% of the capital cost for a new fine chemical plant has to be earmarked for pollution control equipment.  [c.440]

X 10 Btu/yr), or 3.7% of U.S. primary consumption (2). Projections indicate that by the year 2000, the biomass energy contribution will increase to about 4.2 X 10 kJ/yr (1.9 x 10 BOE/d), ie, over 4% of total U.S. primary energy consumption (2). Land- and water-based vegetation, organic wastes, and photosynthetic organisms are categorized as biomass and are nonfossil, renewable carbon resources from which energy, eg, heat, steam, and electric power, and soHd, Hquid, and gaseous fuels, ie, biofuels, can be produced and utilized as fossil fuel substitutes.  [c.9]

The amount of energy that can actually be recovered from a given waste and utilized depends on the waste type. The amount of available MSW is larger than the total amount of available agricultural wastes even though much larger quantities of agricultural wastes are generated. A larger percentage of MSW is collected for centralized disposal than the corresponding amounts of agricultural wastes, most of which are left ia the fields where generated the collection costs would be prohibitive for most agricultural wastes.  [c.12]

Another factor is the potential economic benefit that may be realized due to possible future environmental regulations from utilizing both waste and virgin biomass as energy resources. Carbon taxes imposed on the use of fossil fuels in the United States to help reduce undesirable automobile and power plant emissions to the atmosphere would provide additional economic incentives to stimulate development of new biomass energy systems. Certain tax credits and subsidies are already available for commercial use of specific types of biomass energy systems (93).  [c.37]

Inventories of commercial usage in the United States are available (97,98) Table 32 offers a summary (2). Although most of the data available does not refer to a specific time or year, wood use as a fuel in the industrial and residential sectors is responsible for the largest portion of biofuels consumption in the United States. Those states that have large forest products industries are principal wood energy users. Similarly, states in the Com Belt are the largest fuel ethanol producers. With few exceptions, those states having the most populated cities tend to process more municipal soHd wastes by simultaneous disposal-energy recovery technologies. The biomass energy industry covers the entire nation not one state is devoid of commercial biofuels production or utilization. The practical limitations to transport distance of some biomass such as wood, and the requirement for nearby or local processing, correlates with a concentration of biomass energy-processing faciHties by state.  [c.39]

The waste streams created by utility systems tend, on the whole, to be less environmentally harmful than process waste. Unfortunately, complacency would be njisplaced. Even though utility waste tends to be less harmful than process waste, the quantities of utility waste tend to be larger than those of process waste. This sheer volume can result in a greater environmental impact than process waste. Gaseous combustion products contribute in various ways to the greenhouse effect, acid rain, and can produce a direct health hazard due to the formation of smog (see Fig. 10.1). The aqueous waste generated by utility systems also can be a major problem if it is contaminated.  [c.291]

When utility waste was considered, it was found that to obtain a true picture of the flue gas emissions associated with a process, both the local on-site emissions and those generated by centralized power generation corresponding to the amount of power imported (or exported) need to be included. In the limit, this basic idea can be extended to consider the total emissions (process and utility) associated with the manufacture of a given product in a life-cycle analysisf In life-cycle analysis, a cradle-to-grave view of a particular product is taken. We start with the extraction of the initial raw materials from natural resources. The various transformations of the raw materials are followed through to the manufacture of the final consumer product, the distribution and use of the consumer product, recycling of the product, if this is possible, and finally, its eventual disposal. Each step in the life cycle creates waste. Waste generated by transportation and the manufacture and maintenance of processing equipment also should be included.  [c.295]

Smith, R., and Petela, E., Waste Minimization in the Process Industries 5. Utility Waste, Chem. Eng., 523 16, 1992.  [c.298]

Again, there are two fundamental ways in which a heat pump can be integrated with the process across and not across the pinch. Integration not across (above) the pinch is illustrated in Fig. 6.38a. This arrangement imports W shaftwork and saves IV hot utility. In other words, the system converts power into heat, which is normally never economically worthwhile. Another integration not across (below) the pinch is shown in Fig. 6.386. The result is worse economically. Power is turned into waste heat. Integration across the pinch is illustrated in Fig. 6.38c. This arrangement brings about a genuine saving. It also makes overall sense because heat is pumped from the part of the process which is overall a heat source to the part which is overall a heat sink.  [c.204]

A major disadvantage of the chlorination process is residual acetic acid and overchlorination to dichloroacetic acid. Although various inhibitors have been tried to reduce dichloroacetic acid formation, chloroacetic acid is usually purified by crystallization (15—17). Dichloroacetic acid can be selectively dechlorinated to chloroacetic acid with hydrogen and a catalyst such as palladium (18—20). Extractive distillation (21) and reaction with ketene (22) have also been suggested for removing dichloroacetic acid. Whereas the hydrolysis of trichloroethylene with sulfuric acid yields high purity chloroacetic acid, free of dichloracetic acid, it has the disadvantage of utilizing a relatively more expensive starting material and producing a sulfur containing waste stream.  [c.88]

Chemical Reaction. Reaction of gaseous pollutants can open up new pathways for recovery. Utilization of alkaline scmbbing solutions to collect acidic gases has been discussed. Nitrogen oxides can be decomposed to N2 and O2 by reaction with H2 or CH. Many odors can be controlled by scmbbing organic compounds with solutions of strong oxidants such as potassium permanganate [7722-64-7] KMnO nitric acid [7697-37-2] HNO hydrogen peroxide [7722-84-17, H2O2 hypochlorites and ozone, O. Gas—soHd reactions such as the introduction of hydrated lime into a S02-containing due gas stream (56) are also feasible although these schemes usually fall significantly short of 100% pollutant removal. Dry injection of soHd sodium bicarbonate [144-55-8] NaHCO, has been studied for removal of both SO and NO from due gas, for HCl removal from waste incineration emission (57), and for other hazardous gases from hazardous waste incineration (58). Flue gas humidification generally aids in achieving a more complete gas-soHd reaction. A volatile vapor pollutant can be rendered significantly less volatile by increasing its molecular weight, such as by vapor phase chlorination. An example of a gaseous pollutant control problem that can be changed to a particulate one is the reaction of gaseous HCl with ammonia to produce NH Cl smoke.  [c.389]

Natural Organics. Organic materials traditionally used as nitrogen fertilizers include manures (animal and human excrements), guano (deposits of accumulated bird droppings), fish meal (dried, pulverized fish and fish scrap), and packing-house wastes including bone meal and dried blood. The nitrogen content of these materials is very low compared to those of chemical fertilizers, but the organic content usually gives a supplementary benefit in physical conditioning of the sod. Use of these materials in the 1990s persists to some extent, but the overall impact is small. It is estimated that of the total fertilizer nitrogen now used worldwide, less than 1% is derived from these sources. Normally, these materials are not chemically treated. Processing consists mainly of drying and pulverizing. Because of pressure toward environmental awareness and utilization of wastes, there is considerable research activity directed toward producing fertilizer from waste materials. Such activity is likely to contribute to waste reduction but is not likely to have much impact on the fertilizer market.  [c.216]

Other mold-based SCP processes that have been iavestigated iaclude utilization of sulfite waste Hquor by I aecilomyces varioti conversion of carob bean waste yg Jispergillus niger com- and pea-processiag wastes by Giotrichium sp. and coffee-processiag wastes by Trichoderma har anum (62). However, none of these processes is practiced commercially.  [c.467]

Investment Opportunities and Capital Requirements. Despite some of the temporary economic problems that confront the biomass energy industry in the early 1990s, several business opportunities are being developed at rapid rates. These projects are distributed across the nation and include landfill gas recovery plants, MSW-to-energy systems, and nonutility power generation that qualifies under PURPA. Conventional combustion technology is utilized in the majority of plants gasification seems to have been largely ignored and should offer several advantages (112). A production tax credit equivalent to 0.48/m ( 3.00/BOE) indexed to inflation and linked to the price of oil is available it amounted to about 0.71/GJ ( 0.75/MBtu) of product gas in mid-1985 (112,129), and can have a significant beneficial impact on the profitability of a biofuels project. The lower the cost of oil, the greater the credit. Taking the most optimistic view of the language in the law, wastes are included in the definition of biomass, so it appears the production tax credit is appHcable to all of the above projects, not just those based on wood and other nonwaste biomass.  [c.43]


See pages that mention the term Utility waste : [c.384]    [c.425]    [c.523]    [c.39]   
Chemical process design (2000) -- [ c.274 ]