Waste Engine Oils

Waste Engine Oils: Rerefining and Energy Recovery, by Francois Audibert

•

ISBN: 0444522026

•

Publisher: Elsevier Science & Technology Books

•

Pub. Date: October 2006

Preface

The importance of oil as a lubricating agent for mechanical parts in motion is well known. Adding oil into the engine of a vehicle and noticing that it turns black upon use is a common phenomenon witnessed by all vehicle owners. Indeed, we know that the life cycle of oil is not infinite even if the efficiency of additives is regularly improved. Thus, oil becomes an unavoidable waste and its collection and treatment naturally become important issues for discussion. Owing to the rules that have been in existence in France since 1979 as well as to the financial support from the government via ADEME and last but not least, to the increasing civic responsibihty of the people, a collection rate higher than 80 % for all waste oil is achieved today. Two elimination methods or more precisely two valorization methods are then applied: on the one hand, combustion, a form of energy recovery used mainly in cement factories, and on the other, regeneration, a recycling of the raw material. A European directive gives preference to the latter method. In the United States and in Japan, there are no rules that give priority to any particular method of treatment. Whatever the method used locally, the choice ultimately depends on technical and economic criteria, obviously keeping in mind the impact on the environment, which should be minimized at all costs. The subject remains topical and other methods are also examined here, for example, the consideration of a possible participation of oil refiners in a consortium. Fran9ois Audibert has worked in this field for a long time now. As a young chemical engineer at the Institut Frangais du Petrole (IFF), where he spent his entire career, he established, among his first professional relationships, close contacts with the Societe Parisienne des Lubrifiants Nationaux (SOPALUNA) and experimented extensively on waste oil regeneration. Later he was in charge of various studies in the development of refining processes and of the optimization of industrial thermal equipment. He thoroughly researched this subject and soon achieved recognition as an expert in the field of waste oil regeneration. He participated in the IFF presentation at the First European Congress on waste oil, held in Brussels in 1976. Other publications followed within the framework of international congresses. Of note was his contribution, in 1992, to a report prepared by Yves Pietrasanta, the then President of the Institut Frangais de VEnvironnement (IFEN), at the request of Segolene Royal, the then Minister of the Environment. To add to his list of achievements, at the request of ADEME, he successfully worked in Martinique,

vi

Preface

Reunion, and Guyana to find a solution for waste oil elimination that was well suited to these territories. As such Fran9ois Audibert is the authority to provide us with indepth information and an understanding of the theme of waste oil. After an introduction devoted to base lubricant oil production, its use, and finally its collection, the author describes, in a complete and pedagogic manner, the various methods of waste oil treatment. Technical, economic, and environmental viewpoints have also been presented. I am convinced that this quantity of technical data will serve as, and will remain a reference and useful guide for authorities as well as for industrialists in the fields of used oil collection, regeneration, and thermal equipment operation.

Alain Feugier Environment Division Manager Institut Frangais du Petrole

Foreword

With the exception of synthetic oils, which account for about 8-10 % of the current automotive lubricating oil market, the lubrication of engines requires highly refined base oils with functional additives. While the other fractions produced from crude oil are intended for combustion or chemical transformations, the physical properties of additive-formulated base oil should be protected as much as possible during its use in an engine. The friction owing to the movement of mechanical parts and the temperature at which an engine operates, entail however, a deterioration and the partial degradation of additives which consequently transform a noble product into a product devalued by the presence of impurities, such as soot because of incomplete fuel combustion. For some time, however, the manufacture of high-pressure direct injection engines reduced the amount of soot formed. After the Second World War, the priority was to regenerate these oils with the aim of saving raw materials. This preoccupation justified the existence of a collecting organization regardless of any ecological considerations. It was important that the collecting organization process was selective to retain the two fundamental characteristics of oil obtained from refineries: the viscosity index and the freezing point. Later, refinery development in France and international exchanges, by launching new sources of supply of base oils on to the market, encouraged competitive valorization, i.e., energy recovery taking into account energy saving. Considering the two main methods of valorization, and its different local uses, a complete picture of collecting, waste oil analyses, numerous commercialized and non-commerciahzed processes proposed, and the main energy recovery techniques becomes necessary. For academic purposes, and to provide the reader with a complete overview of waste oil treatment, we describe in Chapter 3 the fundamental physical and chemical treatments appUed to waste oil, for example, thermal treatment, vacuum distillation, deasphalting, ultrafiltration, or catalytic hydrogenation as a finishing treatment. Some economic data of investment and operating costs are also explored, including a study of the impact of certain variables on a return on investment (ROI) such as the annual treated tonnage, the raw material cost, and the selling price of regenerated oil. Concerning process economics, the economic situation of 2005 must be mentioned; in July, the high price of crude oil reached $70 barrel. If we do not pay to much attention to the present fluctuations, it is generally agreed that this price could vary between $50 and

viii

Foreword

$80/barrel. Taking into account this situation we have reassessed the different costs of utiHties, heavy fuel oil, chemicals, and also the base oils produced. My particular thanks to Dr. Pierre Trambouze, former director of the Institut Frangais du Petrole R&D Centre in Solaize (Lyon), who followed the development of research projects in the field of refining and waste oil treatment methods and agreed to review this book. Thanks are due also to my colleagues at the Institut Frangais du Petrole who helped me in this project, in particular, Mr. Frederic Morel, Remy MarceUn, and Gilles Brocchetto (support in R&D), Jacques Denis and Jean Claude Hipeaux (expertise in additives), Sigismond Franckowiak (economic evaluation). I am also grateful for the logistic support provided by Andre Deschamps, Director of Relations for small- and medium-sized industries. My thanks as well to the Agence de VEnvironnement et de la Maitrise de VEnergie for the indirect help that the agency brought in entrusting to Institut Frangais du Petrole the investigations I undertook, regarding DOM-TOM waste oil energy recovery. My thanks also to the people who welcomed me in their companies and to the institutions concerned with the oil profession, environment, or rerefining such as the Union Frangaise des Industries Petrolieres, the Centre Professionnel des Lubrifiants, the Centre Interprofessionnel Technique d'Etudes de la Pollution Atmospherique, and the Chambre Syndicale du Rerqffinage.

F. Audibert

Acronyms

ADEME API CAVEP CBL CEA CEP CFR CITEPA CONCAWE COV CPL DAO DCH DIS DMSO EDTA ELV EPA FCC FOD FILEAS GEIR GTAP HDI HSC HVF IFEN IFP KTI LCV

Agence de rEnvironnement et de la Maitrise de I'Energie American Petroleum Institute Le Comptoir d'Achats et Ventes de Produits Petroliers et Chimiques Compagnie des Bases Lubrifiantes Commissariat a Tenergie atomique Chemical Engineering Partners Compagnie Fran^aise de Raffinage Centre Interprofessionnel Technique d'Etudes de la Pollution Atmospherique Conservation of Clean Acid and Water in Europe Compounds Organic Volatile Centre Professionnel des Lubrifiants Deasphated oil Direct contact hydrogen Dechets Industriels Speciaux Dimethyl sulfoxide Ethylene diamine tetraacetic acid Emission limit value Environmental Protection Agency Fluid catalytic cracking Fuel Oil Domestique Filtration Experimentale Assistee par Fluide Supercritique Groupement Europeen des Industriels de la Regeneration General Tax on the Polluting Activities High-pressure direct injection High-sulphur content High-viscosity fuel Institut Fran9ais de TEnvironnement Institut Fran^ais du Petrole Kinetics Technology International Life cycle analysis

XVI

LHSV LHV LPC LPG LSC MEK MOC MRD NM2P NORA NPRA NS NTP PAO PCA PCB PCDD PCDF PET PNA PTFE ROI RTFOT S AE SBS SIW SOPALUNA SOTULUB SSU TAN TBN TCDD TDA TFE UF UFIP UFP UOP VD VI VLSC VR

Acronyms

Liquid hourly spatial velocity Lower heating value Lube Oil Processing Corporation Liquefied petroleum gas Low-sulphur content Methyl ethyl ketone Mohawk Oil Company Mineralol Raffmerie Dollbergen A^-methyl-2-pyrrolidone National Oil Recyclers' Association National Petroleum Rerefmers' Association Neutral solvent Normal temperature and pressure Poly-a-olefms Polycyclic aromatic Polychlorobiphenyl Polychlorodibenzodioxine Polychlorodibenzofurane Petrol equivalent tonnes Polynuclear aromatics (cf. PCA) Polytetrafluroethylene Return on investment Rolling thin film oven test Society of Automotive Engineers Styrene-butadiene-styrene Special industrial waste Societe Parisienne des Lubrifiants Nationaux Societe Tunisienne de Lubrifiants Second Saybolt Universal Titration acid number Titration base number Tetrachloro-/7-dibenzodioxine Thermal deasphalting Thin-film evaporator Ultrafiltration Union Fran^aise des Industries Petrolieres Union Fran9aise des Petroles Universal Oil Products Vacuum distillate Viscosity index Very low-sulphur content Vacuum residue

Table of Contents

PART I FROM FINISHED LUBRICATING OIL TO WASTE OIL

Chapter 1. Base lubricating oil manufacturing

Chapter 2. Oil use in the engine, collect and controls

PART II USED ENGINES OILS REREFINING

Chapter 3. Oil composition and the treatment steps required

Chapter 4. Main processes available (industrialized or not)

PART III ENERGY RECOVERY FROM ENGINE WASTE OIL

Chapter 5. Engine used oil combustion, alone or mixed with other fuels

Chapter 6. Other valorizations

Chapter 7. Waste oil rerefining and combustion comparison in terms of TEP saved

Introduction

The oils considered in this book are essentially black used oils, the majority of which have been obtained from car or truck engines. Industrial waste oils are not subject to organized and selective reclamation in the same way as engine oils are. Their applications are varied and can be: • • • • •

reclaimed after a rough filtration treatment, centrifugation, or de-emulsification; mixed in limited amounts with waste engine oil; burned in some industrial sites (subject to authorization); disposed of by incineration (necessary for highly polluted oils); used as lubricant (used in grease, general lubrication, two strokes engine, other uses, etc.).

The relative importance of these two types of oils can be assessed from table 1 that clearly shows the prevalence of engine oils (462,479 t/year) in new oil production (888,771 t/year) and consequently that of waste engine oil (information supplied by the Centre Professionnel des Luhrifiants). This difference increases after use, taking into account the wider dispersion of used industrial oils. Indeed, the average percentage of oil recovery is 20-30 % for very fluid oil, machine oil, cutting oil, compressors, two-stroke engines, greases, etc. On the other hand, the recovery rates are higher for turbine and transformer oils (60-90 %) but their low tonnages do not reverse this trend. The sources of black waste oil collected are shown in figure 2.2. Figure 2.1 represents various types of potentially recoverable oils. Some definitions The terminologies most frequently used regarding various types of oils are: • Base oil: new oil produced by oil companies. • Finished base oil: as above but with the required additives package. • Contaminated oil: generally new base oil accidentally mixed with other substances. Also referred to as impure oil. • Black waste oil: derived from engine oils and from some industrial lubricants (metal tempering, heating oil, etc.). • Clear waste oil: hydraulic, turbine, and insulating oil. • Decontaminated or purified oil: oils cleared of their impurities but not having recovered the characteristics of base oil.

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Table 2.4 Changes in chlorine and lead contents in waste oils with time (passenger cars). Chlorine content (ppm) on crankcase sample - ESSO, lubricant Mileage before oil change Car 505 Peugeot Leaded 4,700 gasoline Car 405 Peugeot Unleaded 6,250 gasoHne

Jan. 89 740

Sep. 89 600

Aug. 91 736

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Leadc ontent (ppm) on Crankcase sample - ESSO lubricant Jan. Car 505 Sep. Aug. Peugeot 89 91 89 Leaded 4,700 >3,000 >3,000 3,276 gasoline Car 405 Peugeot Unleaded 6,250 gasoHne

Sep. 92 3,147

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Dehydrated collected oil Country Europe Europe France (year) (1987) (1989) (1991) Mixed Diesel petrol engine oil Chlorine 750 236 736 (ppm) 2,000 3,276 Lead 51 |(ppm)

France (1998) Mixed engine oil 500 202

USA USA Service (1995) (1995) station Mixed Mixed (2001) engine engine oil oil 290 — 180 51

1. Driving on roads or highways - moderate low-temperature starting.

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saturated compounds and VI > 120 for class III), a catalytic hydrotreatment under sufficient pressure conditions appears to be the only solution. To make the comparisons more clear, the production of waste, gasoline, and diesel oil are assumed to be the same. • Scheme A, corresponding to the conventional sulphuric acid treatment, is by far the one that has been most applied and that is still implemented in many countries, especially for small-scale plants. • Scheme B is an improved version of scheme A. The thermal treatment makes it possible to reduce acid consumption by 50 wt% and acid sludge by about 30 wt%. This scheme gives a significant yield improvement. • Scheme C has been a successful scheme for a long time, applied in Italy, but which continues to use some acid. This scheme gives good yield. • Scheme D is characterized by the installation of the vacuum distillation upstream from the clay treatment step. This column must distill oil at a relatively low temperature with a rather short residence time. This upstream vacuum tower has been satisfactorily operated by Viscolube SpA (Italy) owing to the incorporation of appropriate additives (anti-sludge and anti-corrosion). After distillation, the oil is separated from its impurities by adsorption on bleaching clay before separation into fractions. In this scheme, acid is not used, but there is an oil fraction remaining in the vacuum residue often marketed as asphalt. • Scheme E is an optimization of scheme D with the elimination of diesel oil before vacuum distillation operated in the pressure range of 1-10 Torr, often coupled with a TFE. Some licensors claim that they do not need a finishing step for this scheme when the appropriate additives are used. If the amount of clay used in the clay adsorption step is reduced or if this step is dropped completely, then the yield is improved. • Scheme F differs from scheme E with respect to the vacuum residue deasphalting step. Since the viscous oil fraction is recovered here in this scheme, it is not necessary to have a vacuum as high as in the case of scheme D or scheme E. The recovery of the heavy oil fraction (called bright stock) increases the yield. In schemes E and F (without clay adsorption), the operating conditions of the hydrotreatment should be selected depending on the oil characteristics required. Figure 3.20 shows the evolution of rerefining scheme with time - yield improvement and ecological constraints (see Table 3.14).

Chapter 4

Leading industrial and non-industrial processes

INTRODUCTION This chapter describes the different processes that exist on the market. About half of them have led to an industrial application. Some of them appear very similar, the difference being in the process implementation or in the use of additives often progressively perfected and patented. Every process generally comprises of a series of successive treatments: thermal treatment, vacuum distillation, deasphalting, UF, catalytic treatment, and bleaching on clay (each of which was described in detail in Chapter 3). For these different processes, the inlet feedstock is waste engine oil, relatively constant in quality if the collection has been done correctly. The objective is to obtain a base oil divided into fractions of different viscosities to get marketable lubricants after blending with additives. In the following three cases, we have described only sections of the process: • extraction of aromatic compounds from oil by methylpyrrolidone (Bechtel and MRD processes); • extraction of metals and halogens by reaction with molten salt eutectics; • oil UF through membranes (CeraMem technique).

4.1 MEINKEN PROCESS: A STANDARD PROCESS INVOLVING SULPHURIC ACID AND CLAY Considered for a long time as the standard process, it remains the most globally applied. However, its application is on the decline, and is even prohibited in industrialized countries, for ecological reasons.

92

Chapter 4. Leading industrial and non-industrial processes

4.1.1 Process description After a coarse filtration to eliminate particles, for example, >3 mm, the oil is processed as follows:

4.1.1.1 Dehydration Dehydration is almost always the first step. The temperature is of the order of 160-180°C at atmospheric pressure. Heat is supplied by steam or heated fluid through a heat exchanger. The dehydration column is in two sections: in the lower section, oil is pumped at a high flow rate to avoid formation of deposits and oil cracking by ensuring a good heat transfer. A part of the oil is injected at the top of the upper section where dehydration is achieved. This column helps to eliminate variable amounts of water in the lower section and, finally, dehydrate the oil in the upper section. The lighter fractions removed at the top are used as fuels (fig. 4.1 A). 4.1.1.2

Acid treatment and clay adsorption

Dehydrated oil is cooled to about 30°C before reacting with sulphuric acid. Settling time is of the order of 24 h. Decanted oil is mixed with clay before injection into the hightemperature vessel, (high-speed flash boiler), heated at 270°C by a heated fluid to avoid superheating of the oil. During clay treatment, small acid droplets as well as sulphonic acids and oxidized or sulphurized products resulting from acid action in suspension are coalesced and adsorbed. Diesel and spindle oils are removed at the top and the oil at the bottom is cooled to a maximum of 120°C before filtration. The pressure in the vessel is 80 mmHg. According to this process, clay consumption is of the order of 3.5 wt% of the settled oil (fig. 4.1 B).

4.1.2 Waste production The nature and amount of waste produced by the Meinken process are as follows: • • • •

Process water rejected: about 130 kg/t of waste oil. Gas production (gas recovered in vacuum circuits): about 40 Nm^/t. Acid sludge: about 170 kg/t. Used clay (oil retention 100%): 31 kg/t.

Waste water and gas are fed into a furnace heated to 1,000°C, which ensures the notable destruction of phenols. Acid sludge and used clay are burned in a furnace equipped with a dust removal system and Hme washing. Storage and elimination of calcium sulphite and sulphate resulting from the previous treatments must be properly done. Several solutions were proposed. In Sweden, acid sludge was neutralized with a 50 % soda solution, and then channelled to a sulphate production plant where it was incinerated with paper mill black liquor. The sodium sulphate formed was transformed into sodium sulphide used in the manufacture of cellulose in the firing reactor. Another application consisted of introducing acid sludge into pyrite roasting furnace for the

Chapter 4. Leading industrial and non-industrial processes

Waste oil

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93

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Chapter 4. Leading industrial and non-industrial processes

production of sulphuric acid. Finally, application in the cement industry is often mentioned. To conclude, the Meinken process was and remains a widely used process. It is an optimized version of the standard acid and clay process. The acid withdrawal, because of the acid sludge production and the cost of used clay elimination, has led to the installation of a vacuum tower upstream and the use of catalytic hydrogenation of distillates, and possibly of deasphalted vacuum residue in the most complete rerefining scheme.

4.1.3 Process improvements made by Meinken For many years, acid consumption has been of the order of 8-10 wt% of dehydrated oil. Later, the increasing additive content in engine oil led to an increase in acid consumption and a corresponding increase in the acid sludge formed. This situation drew extensive criticism, and led to a decrease in acid consumption in a number of companies. The strategies employed by Meinken were as follows: • Applying a thermal treatment of adjusted severity to oil in order to destabiUze the dispersing additives. According to this procedure, the acid consumption is reduced by around 50%. • Alternatively, after dehydration, a falling film vacuum distillation can be used to give distillates that consume considerably less acid; for example, 3 wt% and about 3 wt% of clay. However, the second solution does not prevent the production of vacuum residue that concentrates waste oil metals and metalloids. This is true of all processes; the final residue can vary from 6 to 20 wt% depending on the processes employed. Remark. In the 1970s, following the example of Meinken, SOPALUNA and IMPERATOR mastered their own contact process that produced diesel oil, spindle oil, and heavy oil for engine use.

4.2 MATTHYS-GARAP PROCESS 4.2.1 Introduction In the 1960s, although the motorway network was not fully developed, engines were subjected to more severe work conditions and this led to the need for more complex additive formulations to ensure correct engine lubrication. The development of dispersing additives makes it considerably more difficult to precipitate the impurities by sulphuric acid that was generally used. Thus, regenerators had to increase the amount of acid at the expense of oil yield, thereby simultaneously increasing the production of acid sludge. Generally, regenerators added acid to the bulk oil after removal of gasoline and water in the preflash column before vacuum distillation with clay and filtration at moderate temperature. This kind of processing was simple and practised, especially by SOPALUNA in Paris, IMPERATOR near Lille, and also by numerous foreign regenerators.

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Figure 4.2 Matthys-Garap process.

A special feature of the Matthys process was the fractionation of dehydrated oil directly in the vacuum tower and the consequent production of oil fractions and residues at the bottom of the column before acid and clay treatment. Figure 4.2 represents a simplified diagram of the entire process.

4.2.2 Process description The process implies three stages of centrifugation that led Matthys to collaborate with Garap, which speciaHzed in centrifugation. The process comprised of the following stages: • Settling or centrifugation. • Atmospheric distillation (or preflash) at 180°C to eliminate water and light hydrocarbons. • Vacuum distillation giving distillates and column bottom residues. • Hot centrifugation of the column bottom to remove metal compounds and asphalt. This elimination was facilitated by the destabilization of dispersing additives caused by the thermal treatment carried out at the bottom of the column at 360°C. • Continuous acidification of oil fractions and column bottom residue. • Separation of acid sludge by centrifugation. • Neutralization and bleaching of oil fractions at a suitable temperature.

96

Chapter 4. Leading industrial and non-industrial processes

The centrifugation of the column bottom residue, to be effective, was carried out at 200/250°C at an acceleration of 7,500^. Figure 4.2 shows the various oil fractions obtained, and indicates some temperatures as well as added percentages of acid and clay.

4.2.3 Conclusion In the past, Matthys used reclaiming equipment not specifically designed for waste oil rerefming. The implementation of a vacuum column upstream from acidification was not the simplest solution, considering the large amount of column bottom residue production from where it becomes necessary for the oil to be extracted by centrifugation. Nevertheless, Matthys has shown its know-how in the development of a process widely implementing centrifugation in viscous media, which remains a delicate technique. If, today, regeneration still includes vacuum distillation upstream from refining, this distillation, especially when using the falling film technique, has been considerably improved and is able to produce a residue representing only 15 wt% of the feed to the column. This improvement makes it possible to recover more heavy oil as heavy distillate and produces a concentrated residue, generally used as an asphalt component or fuel. Furthermore, additives are used to reduce corrosion and deposits in the column, which can cause a damaging shutdown in production.

4.3 ECOHUILE PROCESS The information reported here results from the different contacts established in the past with this company and also from the data supplied to Ecobilan for a study based on the life cycle analysis carried out in 1997-1998 at the request of ADEME. More recent information is not available. However, this company has realized an important investment in the vacuum distillation column and stopped clay treatment.

4.3.1 History On Lillebonne's site (Rouen), currently operated by Ecohuile, several companies have been active in the field of regeneration. In the 1960s, the Matthys-Garap collaboration worked on a process, the essential characteristics of which are described in Section 4.2. The site was then operated by CBL: the principal shareholders were Burma (34 %), Condat (14 %), Elf (10 %), Total (10 %), Motul (10 %), and Scori (10 %). In the 1980s the technical collaboration of CBL with Total and CEA aimed at developing UF (see the Regelub process - Section 4.12) followed by catalytic hydrotreatment. This process could not be industrially applied and was practically abandoned in 1986, owing to the declines in the price of crude petroleum and the dollar, with a correspondingly marked decline in the selling price of rerefined base oils. At the same time, the parafiscal tax on new oil was implemented in order to finance the collection of waste oil. In 1992, after SOPALUNA,

Chapter 4. Leading industrial and non-industrial processes

97

IMPERATOR, and UFP closed down, CBL was the only company still operating a partially obsolete rerefining plant, with a vacuum distillation producing a bottom residue representing 40 % of the feed to the column. Soon, CBL went bankrupt as well. Then, Lillebonne's site was taken over by a holding company (Financiere 97). In 1994-1995, this new company proceeded to update the vacuum column to improve the quality of distillates and reduce the column bottom residue from 40 to 15-20%. In addition, the following technical and environmental improvements were made: • Prohibition of the use of sulphuric acid, which eliminates the problem of combustion of sludge containing on average 14 wt% sulphur. • Energy recovery from various effluents (used clay, waste water, and vacuum residue as supplement) by combustion in a rotating furnace and effluent gas cleaning in electrofilters. • Development of instrumentation and automation of various equipments. • Clay adsorption was banned on 1 January 2001; this simultaneously increased the oil yield and made the treatment of the corresponding oil waste unnecessary.

4.3.2 Waste oil supply to the plant Ecohuile reclaims about 80,000 t/year on the Lillebonne site with an average collection of about 330 km around (ADEME data). The controls at the truck arrival area determine the acceptance of the waste oil received. At the entrance, the criteria are as follows: Characteristics Specific gravity (kg/m^) Water (wt%) Chlorine (wt%) PCB/PCT (mg/kg)

Measurement method ASTM D 4052 NFT60 154 NFM 03 009 XPT60 184

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Chapter 4. Leading industrial and non-industrial processes

Table 4.1 B Produced gasoil analyses. Parameter

Standard

Specific gravity (kg/m^) Viscosity at 20°C (mmVs) Corrosion (copper test) TAN (mg KOH/g) Sulphur (wt%) Cetane index (calculated) Ash content (wt%)

ISO 12185 NF T 60-100 ISO 2160 NFT 60-112 D2622 ISO 4264 ISO 6245

Diesel oil

Specifications 2002

846 5.25 Class lA 0 0.51 50 810and 3 and >j ^4m Ceramic membranes (300°C-10bar-10m/s) Cracked HC 1.2 ^ Spindle

72.4 Vacuum tower

Neutral

H2 (Total oil 71.7) Bright stock

Oil fraction yield : 92 %)

Figure 4.18 Regelub process. flocculated particles resulting from the thermal treatment before centrifugal separation. The step of centrifugation was later abandoned, because it was demonstrated that the presence of suspended materials increases the shearing effect on the concentration of the polarization layer, and so reduces membrane plugging, thereby increasing the flow rate of the filtration.

138

Chapter 4. Leading industrial and non-industrial processes

6. Finishing is achieved by catalytic hydrogenation which eliminates soluble oxidized compounds and residual nitrogenous compounds which must be removed to obtain a suitable discolouration. In practice, hydrogenation bleaches the oil and sHghtly improves some characteristics such as the Conradson carbon, TAN, TBN, sulphur, and ash content. 7. Finally, vacuum distillation is used to separate hydrogenated oil into fractions. Heavy oil, also known as bright stock, is removed at the bottom of the distillation column. UF is achieved through membranes (or barriers) made of ceramic material resistant to temperatures from 250 to 300°C and pressures up to 20 bars. As mentioned in Section 3.2.2.3B, these tubular membranes are made of carbon and assembled in tubesheets as in shell-and-tube exchangers. The tangential velocity of the fluid is high enough to prevent plugging of the membrane by the particles accumulated on it. Table 4.14 shows the characteristics of the oil obtained before its separation into fractions. The feedstock analyses are not reported, but were standard. In order to appreciate the quality of finished oil, we have provided in the same table the analysis of a representative oil collected simultaneously for Solunor. The date of this analysis explains the presence of barium and especially lead.

4.13 SOLVENT EXTRACTION PROCESS USING N-METHYL-2-PYRROLIDONE Source documents: • Hydrocarbon processing, November 2000. • Website: www.bechtel.com. • Direct information exchange with Mineralol raffinerie Dollbergen (MRD) process managers.

4.13.1 Introduction The Bechtel process is a refining process apphcable to waste oils as well as to refineryproduced distillates. The process selectively removes aromatic compounds and compounds containing heteroatoms (e.g., oxygen, nitrogen, and sulphur), using A2-methyl-2-pyrrolidone (NM2P) as solvent, and competes with the phenol or furfurol extraction process. From an environmental point of view, the Bechtel process is better than all other directly competing processes. This situation explains why the implementation of the Bechtel process led to the replacement of the phenol or furfurol extraction process. MRD has particularly been involved during the last decade or more in the field of PNA extraction with respect to waste oil rerefining.

4.13.2 Application of the process to waste engine oil Aromatic solvent extraction is generally applied to vacuum distillates to improve the VI (or the multi-grade property) of base oils produced in the refinery. This refining process

Chapter 4. Leading industrial and non-industrial processes

139

Table 4.14 Regelube process - refined oil characteristics (total fraction).

Parameter

Viscosity at 40°C (mm^/s) Viscosity at 100°C (mmVs) VI TBN (mg KOH/g) Conradson carbon (w %) Sulphated ash (estimate) (wt%) Insoluble pentane (wt%) Sulphur (wt%) Colour ASTMD 1500 Metals and metalloids (ppm) Ba Ca Mg B Zn P Fe Cr Al Cu Sn Pb V Mo Si

1 Na

Rerefined oil before fractionation into oil fractions (Regelub process) in 1984

Collected oil supplied to Solunor Co (Typical oil fraction) in 1984

5095 7.4 106 0.05 0.1 0.005 0.005 0.23 4

92 11.6 124 5.2 1.85 1.5' — 0.85 < 8 (black) 6,096 112 1,312 172 22 1,123 1,252 110 4 9 25 33 1,870 n 00

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Chapter 4. Leading industrial and non-industrial processes

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Water treatment

Guard filter To hydrotreating |\

f 1( Filtration additive

Hydrogen recirculation

Oil production

Figure 4.20 A. PROP process (Phillips Petroleum) - demetallization. B. PROP process (Phillips Petroleum) - hydrotreatment.

Chapter 4. Leading industrial and non-industrial processes

145

Waste oil is first mixed on-line with an aqueous solution of diammonium phosphate and, separately, with a chemical agent described differently, according to the patents (polyhydroxy compound, polyethoxyalkylamine). Reactions take place according to mechanisms suggested in Section 3.2.1.3. The phosphates produced by the exchange of ammonium with metals in oil are only slightly soluble in the two phases (aqueous and organic) and precipitate into the lower aqueous phase. The reacted oil stream essentially becomes a slurry with approximately 1 % solid content. Water and light hydrocarbons are removed at the top of the second and third reactors. The upstream reaction with diammonium phosphate is achieved according to a certain procedure: a trend towards increasing temperature and decreasing pressure to eliminate water and light hydrocarbons is observed. The process is illustrated in figure 4.20 A. The successive couples T l - P l , T2-P2, and T3-P3, correspond to specific conditions at each stage. The residual contents of zinc and phosphorus (owing to the presence of antioxidant additives (zinc dialkyldithiophosphates) are eliminated after a thermal treatment followed by filtration with an additive. At this stage, the oil can be catalytically hydrofined, after alternate treatments through two parallel guard reactors. The catalyst is standard with nickel-molybdenum as active metals. As mentioned earlier, hydrotreatment removes sulphur, nitrogen, oxides, and chlorine and bleaches the oil which is then stripped to eliminate volatile products formed during the catalytic reactions and to adjust the oil flash point. The recycled hydrogen is washed with water and soda to remove compounds such as H2S, NH3, and HCl resulting from the catalytic reactions.

4.14.2 Process characteristics The demetallization reaction occurs at about 150°C under a pressure adjusted to make it possible to eliminate water in the demetallizing reactors 2 and 3. Of course, the flocculating agent being in an aqueous phase, so it is useless to dehydrate the crude oil in the previous step, as is generally done in other processes. The quantity of flocculant added is equal to 100 wt% of the ash content of the oil. It will be noticed, however, that this kind of precipitation with flocculants is carried out in two or three stages (three reactors in this case). The cost of these chemical reactors is however moderate owing to the low pressure required (close to atmospheric pressure). The oil is then heated at 180°C before filtration, according to the above-mentioned patent. The hydrotreatment section is standard and patent no. 3,930,988 lists the following conditions of operation in the example given: • feed volume/catalyst volume/hour (vvh): 1.3 • temperature: 360°C • pressure: 50 bar • recycled hydrogen: 214 L/L Table 4.16 shows the efficiency of a thermal treatment before filtration stage. Table 4.17 shows analyses of two industrially rerefined oil samples according to the Phillips process.

146

Chapter 4. Leading industrial and non-industrial processes

Table 4.16 Effect of thermal treatment on filtration efficiency after flocculation (PROP process).

Parameter Metals and metalloids (ppm) Al Cr Cu Fe Mg Pb Si Ba Ca P Zn Sulphated ash content (wt%) Filtration velocity (L/h/m2)

Filtrate without upstream thermal treatment

Crude waste oil

21 9 29 259 556 3,610 23 123 1,340 990 1,050

2 8 300 200 0.95 0.07 — — 0.05

203 0.19 615 —

— — — — — —

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Chapter 5

Combustion of waste engine oil with or without other fuels

5.1 WASTE ENGINE OIL COMBUSTION (NO BLENDING) 5.1.1 Overview Important restrictions are imposed on the combustion of waste oil classified as hazardous waste. This means that energy recovery is and will be, in most cases, subject to additional costs of effluent gas treatment. The need to satisfy the emission limit values (ELVs) for this waste seriously limits its application. Waste engine oil, essentially composed of hydrocarbons, is an excellent fuel; furthermore, it does not contain a heavy residual fraction characteristic of heavy fuels. This characteristic explains why the flue gas produced by oil combustion does not contain unbumed soUd carbon particles called cenospheres. Some physical properties of oil (see the tables in Section 2.3) improve the handling and combustion of this oil with the following advantages: • A low viscosity that allows the oil to be injected at about 70°C into a standard burner instead of 130°C for the no. 6 fuel oil. • A sufficient fluidity to be stored and pumped at about 10°C instead of 50-70°C for the no. 6 fuel oil. • A relatively low-sulphur content (LSC), which makes the oil comparable to lowsulphur fuel oil (S < 1 wt%). • A high heating value of the order of 39.7 MJ/kg after settling (for example, 3 days at 15°C).

200

Chapter 5. Combustion of waste engine oil with or without other fuels

Compared to saleable fuels, waste engine oil could be ranked as follows: as regards standards, waste engine oil cannot be considered as equivalent to diesel oil in terms of viscosity, distillation curve, Conradson carbon, and sulphur. On the other hand, properties of waste engine oil place it favourably in contrast to low-sulphur no. 6 fuel oil for viscosity (good fluidity), and much lower Conradson carbon and asphaltene contents. As well as the advantages mentioned above, the oil can, however, contain polluting solvents that must be eliminated. Metallic and metalloid compounds must also be eliminated, since they are transformed into oxides carried by the combustion gas and partially transformed into sulphates that are then deposited in the combustion chamber. Additives and the corrosion of engine parts are responsible for this level of contamination, about 5,000 ppm (wt) (see tables 2.1 and 2.2).

5.1.2 Detailed characteristics of waste oil combustion When local economic conditions are favourable for combustion and when ecological constraints are satisfied, nothing can prevent oil valorization by this method. The main problems encountered are described below. Suspended particles resulting from certain metallic parts of an engine and very fine dust pass through upstream filters, calibrated to only 150 or 250 |Li. As a consequence, a more rapid wear of burners, injectors, low-pressure feeding pumps, and high-pressure burner pumps is observed. Manufacturers dealing with waste oil generally select equipment that is more resistant to abrasion and are accustomed to periodic change as necessary. Mouvex or similar pumps give satisfactory performance when used with waste oil. All the metals and metalloids present in the oil and mainly due to additives (after filtration) generate fly ash [Audibert and Fouquet, 1990] essentially constituted by oxides of elements formed during combustion and then partially sulphated by the fuel sulphur at the level of the boiler tubes and walls. A small fraction of the fuel sulphur is converted into sulphates in the combustion chamber [Walsh et aL, 1986]. The oxides prevalent are those of calcium, zinc, phosphorus, and magnesium (lead having practically disappeared). Moreover, we notice that for waste engine oil, the ash content corresponds well (by weight) to twice the metal and metalloid content because of their transformation into oxides. As a consequence, ash emission can be predicted from the analysis of metals and metalloids contained in the oil. This fly ash is found in the gas effluent and in the combustion chamber. In the case of furnaces and boilers, a film of white deposit covers the chamber and the tubes (the film is white when the oil is not mixed with heavy fuel oil), and it is necessary to blow steam or compressed air after 2 or 3 days' operations or more, depending on the equipment. Table 5.1 shows the average analysis of deposits taken from various points of a water tube boiler of 2 MW (Babcock FM T - 19) after a 24 h operation with waste engine oil in 1980. The presence of vanadium and nickel is due to the stardard operation of this boiler with heavy fuel oil. Since 1980 the use of barium has been banned because of its toxicity. Remark. Ashes are to be distinguished from sediments that correspond to solid impurities, which are separated on a filter under conditions defined by a standard. Only expensive treatments such as vacuum distillation, UP, or deasphalting for removing metals and metalloids would really decrease the content of fly ash in combustion gas. Some investigations

201

Chapter 5. Combustion of waste engine oil with or without other fuels Table 5.1 Boiler deposit analyses after waste engine oil combustion Measured Ba elements

Ca

P

Zn

Mg

Al

wt%

4.1

4.5

4.1

1.2

0.4 0.02 0.07 1.1 1.2 0.9

3

B

Cr

Cu Fe Ni

Pb

Si

6.5 0.7

Sn V

S

0.1 1.3 2M

1. Estimated value-when burning oil, the conversion of SO^ into SO3 is not catalyzed by vanadium and nickel (absence of these metals). mention the removal of metals and metalloids by reaction in molten salt eutectics. However, there appears to be no industrial application of this technique.

5.1.3 Elemental analysis and combustion calculation Before proceeding to standard combustion calculations, fuel elemental analysis must be done. To compare waste oil with common fuels, table 5.2 gives elemental analyses of waste oil, diesel oil, and three types of heavy fuel oil with different contents of sulphur: S < 4 %, S < 2 %, and S < 1 % [ATEE, 1995]. With the results of the elemental analysis of a given fuel, combustion calculations can follow - consisting of determining, for a given excess volume of air, the volumes of air required and of flue gas (dry and wet) produced as well as the flue gas composition. The knowledge of the dry gas volume is useful to express pollutant concentrations per cubic metre (Nm^) of dry gas. The calculations presented in table 5.3 are based on 1 kg of fuel (data for waste oil and no. 6 low-sulphur fuel oil are given). Results are given for 3, 10, and 17 % (by volume) of oxygen in dry flue gas to show the influence of this parameter on the dilution of gaseous constituents and dusts in stack gas. These results are interesting to know because in the waste oil energy recovery according to different ways, like boilers using fuel oil, power plants using coal, cement works, asphalt plants, the emission limit values of constituents are given for oxygen concentration in dry gas of 3 to 17% according to the types of installations cited above. Naturally, to conform to current emission standards the oil should be burned in installations that remove dust from gases resulting from oil combustion, irrespective of the process used or in any case, in installations equipped for the treatment of exhaust gases. Furthermore, combustion conditions should not encourage the formation of dioxins and furanes. Gas compositions resulting from traditional calculations are represented in table 5.3. In the case of waste oil combustion (with 3 % of oxygen in dry gas), the removal rates required to satisfy the ELVs characterizing waste oil are presented (EEC directive 2000/76). Remark. The calculations and estimates for NO^, SO2, HCl, dusts, and metals and metalloids are given below: • NOx - NOx formation (resulting from NO oxidation) is controlled by three different mechanisms: o The thermal NO which results from the oxidation of the nitrogen molecule of the air and which is strongly dependent on temperature, Zeldovich's mechanism [Zeldovich, 1947].

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Chapter 6. Alternative valorization

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routes

B. Investment costs^ Parameter

1995 (MM$)

2000 (MM$)

2005 (MM$) 1

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5

5.7

6.6

2.85

3.28

3.8

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10.4 X 10^ ($/year)

Waste oil ($/t)

Vacuum distillate ($/t)

5,441 466 1,870 7,777 521 302 187 1,010 8,787

45 4 16 65 4 3 2 8 73

60 5 21 86 6 3 2 11 98

2,078 10,865 2,107

17 91 18 9 8

23 121 23 12 10

110

146

935

Note: Economics ($) - updated mid-2005; base: 120,000 t/year of waste oil; vacuum distillate production = 90,000 t/year. Source: E\f-ToXal 1995 data, updated 2000-updating factor = 1.15, complementary update 2005-coefficient = 1.15. 3. Data from the UFIP.

252

Chapter 6. Alternative

valorization

routes

reduced since then, we have presented table 6.2 showing a 50 % reduction in the investment and operating costs for dechlorination (300 ppm of chlorine in the feed instead of 1,100 ppm).

C. Operating expenses It is necessary to add to the pre-treatment cost the cost of transportation from the platform site to the closest refinery equipped with FCC as well as the cost of vacuum distillation. Indeed, the objective is to estimate the total cost of waste oil treatment to produce

Table 6.2 Economic evaluation of oil regeneration in an oil refinery (second case: 300 ppm of chlorine in the feed). Waste oil pre-treatment including dechlorination step (chlorine in the feed: 300 ppm) Investment (million dollars) updated 2005 including offsite costs

8.5

Simplified operating cost Waste oil purchase (transportation + delivery cost: 32.8 $/t) Energy cost Consumables/incineration

X 10^ ($/year) 5,441 466 756

45 4 6

60 5 8

Sub-total variable costs Labour Maintenance and related expenses Tax/insurance

6,663 521 302 187

56 4 3 2

74 6 3 2

Sub-total fixed costs

1,010

8

Total fixed and variable costs

7,673

64

11 0 85 0

Depreciation costs (10 years) + financial costs (10 %)

1,700

14

9,373 2,107

78 18 9 8

19 0 104 23 12 10

97

130

Total pre-treatment cost Transportation to the refinery Vacuum tower operating cost Bitumen credit [Total FCC feed cost

Waste oil ($/t) Vacuum distillate ($/t)

Note: Economics ($) - updated mid-2005; base: 120,000 t/year of waste oil; vacuum distillate production = 90,000 t/year. Source: Elf-Total 1995 data, updated 2000 - updating factor = 1.15, complementary update 2005 = coefficient = 1.15.

Chapter 6. Alternative valorization routes

253

an FCC feed or fuel. Therefore it is advisable to compare the costs of $146 and $130 (related to one tonne of vacuum distillate) with the market prices of available current distillates feeding the FCC or used as fuel.

6.1.2 Valorization into lubricating oils Another interesting method consists of regenerating waste oil as base oil. Obviously, this solution can be considered only in a refinery already manufacturing lubricants. The valorization process is as follows (fig. 6.1, route (2)): • In a process similar to that for FCC valorization, the oil is settled, de-emulsified, dehydrated, and dechlorinated. • The oil is then mixed with a large amount of atmospheric residue. According to the needs of base oil, a suitable fraction of the previous mixture is channelled to the vacuum column of the lubricating oil plant, generally followed by steps for the extraction of aromatic compounds, dewaxing, and a finishing treatment. The other fraction feeds the vacuum column as described earlier. The residual fraction of the waste oil containing metals and sludge is removed with the vacuum residue however be the valorization route used. Remark. An alternative solution could consist, on a suitably chosen site, of producing a large vacuum distillate from waste oil after the elimination of light and bottom fractions. This purified feedstock could be regenerated later in an oil refinery to feed an FCC unit or possibly in a lubricant production plant.

6.1.3 Valorization in refinery presented by CEP"^ At the NORA Congress in Orlando (October 1998), CEP showed its interest in alternative solutions to valorization, subject to economic viability. CEP proposed valorization in the form of FCC feed or diesel oil. The CEP rerefining process operated at Evergreen Oil (San Francisco Bay) is described in Section 4.7. 6.1.3.1

CEP-FCC process

Crude waste oil is treated with a chemical agent according to a process patented by CEP and aimed at reducing the fouling and corrosion problems in the downstream equipment previously mentioned. The oil is then rid of water, gasoline, and diesel oil and separated from its residue in a TEE before entering the FCC unit. This feed, constituted by the waste oil vacuum distillate, is comparable to conventional FCC feedstocks (table 6.3). In fact, an improved version of the Mohawk process, implemented at Evergreen Oil (Section 4.8), involves a decontamination step, before the faUing film distillation, which reduces metals and chlorine content to an acceptable level before feeding the FCC unit.^

4. KhuranaK.C. 5. www.evergreenoil.coin - 2001 data.

254

Chapter 6. Alternative valorization routes

Table 6.3 Comparative analyses of CEP fraction and a standard FCC feed. FCC conventional feed Hydrotreated feed

CEP feed

920 11.48 —

896 11.67 —

890 12.18 5

265 399 496 0.21 — 0.32

249 375 467 0.04 — 0.05

343 421 482 0.32 25 >99.5

>60 >99.5

>80 >99.5

>100 >99.5

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60, but the ball-andring temperature variation is too great (>8). • The Fraass figure after the RTFOT stays at a satisfactory level. The poor water resistance in the compression tests is limited to about 15 wt% of the addition of residue to the asphalt in the absence of an efficient additive.

264

Chapter 6. Alternative valorization routes

6.3.3 Valorization of propane clarified residue by addition to bitumen As in the case of vacuum residue, the objective of these tests was to show the influence of the addition of increasing quantities of propane clarified residue (diluted as mentioned in Section 6.3.1) to a reference bitumen (results in table 6.7). The experiments above have shown the possibility of obtaining bitumen with characteristics at least equivalent to those of the products obtained from direct vacuum distillation. Comparing bitumen specifications in table 6.6 it can be noticed that for the same penetration, the advantages are as follows: • higher ball-and-ring temperature; • lower Fraass temperature; • better penetration number. Similarly, for the same composition of aggregates and the same amount of binder, the characteristics of the asphalt mix obtained are also at least equivalent to that of a standard asphalt mix with, amongst other improvements, a better rutting behaviour (dry conditions). Table 6.8 shows results corresponding to the composition of the aggregates given in the same table. With 30,000 cycles, the rutting of the asphalt mix with the composite binder is lower by 17 % compared to that of the pure bitumen-asphalt mix eventhough it has a penetration lower than that of the composite binder. This study showed an insufficient water resistance in compression tests (Duriez tests), leading to a limit of 15 wt% of the VR addition to standard bitumen. Attempts to find additives for eliminating this drawback were initiated but not pursued. Furthermore, it was verified that the concentrations in heavy metals from the rerefining residue, mixed with standard bitumen, would remain lower than the limit values defined by the standard NF U 44-041. Indeed, there is a residual copper content of the order of 5 ppm weight for a standard of 100 ppm and about 80 ppm of zinc for a standard of 300 ppm. In any case, heavy metals may be considered to be trapped in bitumen. However, to protect the environment it is preferable to use an asphalt mix in an underlayer (or link layer) in order to avoid washing and wear to the surface layer.

6.3.4 Acid sludge valorization In the 1970s, waste oil valorization plants using sulphuric acid were still very common, even in the USA, and acid sludge, generally burned or disposed of in a controlled manner, posed serious environmental problems. In the absence of non-polluting modem processes, the US Department of Energy, in collaboration with the Energy Research and Development Administration granted financial support to Peak Oil Company (Tampa, FL) to study the valorization of acid sludge by a method other than combustion or dumping. The process developed by Peak Oil Company consisted of valorizing acid sludge by mixing it with standard mineral components with the aim of obtaining building materials like bricks or paving slabs, acceptable for appropriate uses.

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50,000 t/year. Yet, a need for smaller installations does exist and the idea of transforming waste oil into a clean fuel that is easy to store and distribute is quite attractive. Although appealing, this latter solution implies an oil contaminant removal rate of 95-99 % and this result cannot be obtained by a simple filtration or centrifugation. As shown in Section 7.2.3, the necessary oil treatments represent a relatively high cost for obtaining a product that faces heavy competition from other fuels. However, as stated previously, only a high crude price could justify the transformation of waste oil into a clean fuel. It may be recalled that the most common energy recovery process is direct combustion of an oil, unmixed or mixed with fuel oil in an appropriate installation with regard to the environment such as a cement factory or a hot-mix asphalt plant (the latter would be subject to further tests and improved flue gas treatment). These installations are characterized by a large mineral volume handling capacity that adsorbs fly ash, with a downstream flue gas treatment to complete the flue gas cleanup step. With this type of valorization, oil is used in this way as the combustion installation ensures cleanup. Aside from these favourable cases for valorization, there could be an open market for the use of demetallized waste oil in common industrial installations, of course this type of valorization is dependent on the crude price.

7.2.1 Waste oil potentiality for the combustion route As described in Section 5.1.1, the relative easy handling and combustion of waste oil make this product very attractive as a fuel and place it favourably compared to the lowsulphur no. 6 fuel, except for the presence of metals. In table 7.2, the comparison of the two fuels indicates specific properties of the product obtained from engine waste oil that could justify a higher selling price than that of the low-sulphur no. 6 fuel oil, if the waste oil is purified. Nevertheless, the same price was assumed for both products in the economic evaluation presented later, to take into account any prejudices against the combustion route.

7.2.2 Definition of clean fuel Waste oil transformed into clean fuel is no longer considered as a hazardous waste, but as a standard fuel and the flue gas resulting from its combustion should satisfy the ELVs defined in the 2 February 1998 decree applicable to all installations under Hcence. The general case and the exceptions are listed in tables 7.3 A and B extracted from the 2 February 1998 decree reported in Appendix 9. In the standard case of combustion in a boiler (category 2910 of the decree) the clean fuel should satisfy the ELV given in table 7.4. To determine the purity level of the oil to be considered as clean fuel, a logical method consists in observing the ELV of each element, imposed on the flue gas emitted. From

277

278

Chapter 7. Comparison of rerefining and combustion routes in terms of saved PET

Table 7.2 Waste oil properties favourable for the combustion route. Compared fuels

Waste engine oil (average properties)

Viscosity at 100°C

8-13 mm^/s

Flash point on dehydrated oil Distillation

150-230°C

Pour point Conradson carbon (ability to form coke) Sulphur w-heptane precipitated asphaltene (ability to form unbumed solids in combustion) Water content Insoluble contents

< 8 % at 250°C 8 t = general case and 200 g/t

Hot-mix asphalt plants 50 mg/m^ Drying industry Heavy goods handling SO2 + SO3 (as SO2)

>25

300 Titanium dioxide Entirely new refineries Existent refineries and extension Urban area Coking works Non-refinery petro chemical plants apart ft-om refinery

100 mg/m^ 50 mg/m^ in ambient air at 5 m far from the source Digestion and calcination 10kg/tTiO2 Acid waste concentration: 500 mg/m^ Average daily flux equivalent 1,000 mg/m^ (applicable on 1 January 2000) Average daily flux equivalent 1,700 mg/m^ (applicable on January 2000) 750 mg/m> 500 mg/m^ if flux > 25 kg/h Sulphurized gas treatment: no ELV but conversion rate > 99.6 {Continued)

280

Chapter 7. Comparison of rereflning and combustion routes in terms of saved PET

Table 7.3 A

(Continued). General case

Sliif%cfsinpp

VJ U MS K t l l V C

ELVi Hourly flux (kg/h) (mg/m3 (cr))

Exceptions - ELV whatever the hourly flux, except contrary indication Combustion installation apart from 20 June 1975 to 27 June 1990 decree

|

Liquid fuel: 3,400 mg/m^ Furnace: see the authority decree taking into account a possible retention Multi fuels separately: ELV stated by authority decree Multi fuels simultaneously: ELV is that of that of the fuel to which the greater ELV is applied

SO2, SO3, H2SO4 oleum

NO + NO2 (expressed as NO2)

>25

500

Existing refineries and extensions Urban area Nitric acid manufacturing

HCland chlorine inorganic compounds (expressed as HCl) Fluorine and fluorine inorganic compound (particulate, vesicular,

>1

50

H2SO4 regeneration with content > 8 %: conversion rate > 9 9 % and 7 kg/t H2SO4 regeneration with content < 8 %: conversion rate > 9 8 % a n d 13 kg/t Other manufacturing with H2SO4 > 8 %: conversion rate > 99.6 % and 2.6 kg/t (at 100 % H2SO4)

Average daily flux equivalent to 500 mg/m^ (applicable on 1 January 2000) 750 mg/m^ 1.3 kg/t HNO3 (100%)

No special case

>5

5 for gaseous compound Phosphoric acid

Gaseous compounds: 10 cmg/m^ (Continued).

Chapter 7. Comparison of rerefining and combustion routes in terms of saved PET Table 7.3 A

(Continued). General case

Substance gaseous expressed asHF)

281

Hourly flux ELVi (kgAi) (mg/m3 (cr))

Exceptions - ELV whatever the hourly flux, except contrary indication

5 for particulate and vesicular compound Particulate and vesicular manufact Compounds: 10 mg/m^ uring, phosphorous, nitrogenous fertilizer Electrolysis Aluminium 1 kg/t Al and 0.85 kg/t Al production (monthly average)

Note: Cr-means reference conditions of temperature and pressure.

7.2.2.2

Example 2: general case - combustion with 3 vol% of O2 in dry flue gas

In table 7.3 B, for a flow rate >0.025 kg/h, the ELV for all the metals and metalloids (Cr, Co, Cu, Sn, Mn, Pb, V, Zn, and Sb) is 5 mg/Nm^ This figure implies a maximum content of these elements of 5 X 14.75, i.e., 74 ppm in the oil instead of 1,400 ppm in waste oil (Ecohuile analysis, 1998), that means a reduction rate of 95 %. In fact, in practice this flow rate of 0.025 kg/h is always exceeded. Indeed, 25 g/h of elements present at a concentration of 1,400 ppm in the oil corresponds to a stream of 17.85 kg/h, which is indeed significantly below the industrial flow rates. In the second example, the clean fuel should not contain >74 ppm of the contaminating elements mentioned above. It should be remembered, however, that the scheduled decline in lead concentration makes it possible to achieve the lower metal reduction rate required. Remark 1. Both examples above aim to illustr^e the calculation method. In practice, it is advisable to consult the various decrees often amended periodically. For equipment between 20 and 100 MW, burning solid or liquid fuel, a new decree came into effect recently. The ELV for elements Sb, Cr, Co, Cu, Sn, Mn, Ni, V, Zn, and their compounds is fixed at 10 mg/Nml It is 20 mg/Nm^ for installations located outside urban areas of more than 250,000 inhabitants. However, according to the new decree, lead is considered separately and its content in flue gas is limited to 1 mg/Nm^ which corresponds to 15 ppm in the oil. Although the lead as a product of leaded gasoline is no longer a concern, quantities of the order of 15-50 ppm still come from the corrosion of engine parts (bearing surface, see tables 2.4 and 2.5) and also from additives. This means that for large installations, waste oil can be advantageously diluted with an amount of no. 6 or no. 5 heavy fuel oil.

282

Chapter 7. Comparison of rerefining and combustion routes in terms of saved PET

Remark 2. A trapping rate of 20 % for particles was assumed, though, in practice, and according to the installations, this rate can vary widely; while always low in a furnace it is able to reach 50-80 % in a boiler. A trapping rate of 50 % was reported for the combustion of waste oil in one survey made in the USA (John J. Yates). However, it is difficult to define a trapping rate of particles in boilers. A clean combustion chamber progressively becomes covered with deposits, when deposits on tubes become too great, they are generally expelled into the atmosphere by compressed air or steam by means of specific tubes sweeps. A large but variable fraction of these deposits escapes this type of cleaning and must be collected in the chamber during maintenance operations. The rate of trapping at 20 % is in fact an average estimation obtained from boiler data.

Table 7.3 B Emission limit value.

Substances

Exceptions - ELV whatever the hourly flux, except opposite indication

General case Hourly flux ELV (kg/h) (mg/m^ (cr))

COVNM^ All the GOV (composes (composes organiques volatiles organiques volatiles) >2 150 non methaniques) All the GOV mentioned (see appendix) >0.1 20 N2O No general case (see the authorization authority decree) CO No general case (see the authorization authority decree) Phosphine >0.01 1 Phosphogene >0.01 1 HCN >0.05 5 Bromine and >0.058 5 gaseous inorganic compounds (expressed as HBr)

All installations

Purification by incineration 50 mg/m^ expressed as total carbon

Hydrocarbon

35 g/m^ storage

Nitric acid manufacture

7kg/tHNO3(100%)

CI2

None

expressed as HCl H2S NH3

Asbestos Cd, Hg, andTi

>0.05 >0.05 >0.05 > 100 kg/year

5 5 5 Fibre 1 Total dust 50 Total (Gd + Hg + Ti)

Only specific cases

|

None None None

None None None New workshops: Electrolysis of alkaline chlorides prohibited involving Hg cathode process (Continued).

Chapter 7. Comparison ofrerefining and combustion routes in terms of saved PET Table 7.3 B

(Continued). >0.001

As, Se, Te Sb, Cr, Co, Cu, Sn, Mn, Ni, Pb, V, and Zn

0.2

Total (As + Se + Te) >0.005 1 All the following elements Sb + Cr +Co + Cu+ Sn + Mn + Ni + Pb + V + Zn >0.025 5

Existing workshops: limitation to 2g (Hg)/ton of chlorine production except if there is a commitment to cancel the use of Hg before 2000 Battery manufac Lead recovery: Pb, 1 ture including Pb, mg/m^; Cd, 0.05 mg/m^; Hg, 0.05 mg/m^ Cd, or Hg None Cu melting electro Vat furnace when melt lytic furnace ing: further to 10 mg Cu and its compounds/m^ Combustion insta nations apart from decree of 20 June 1975 and decree 27 June 1990 Vinyl chloride polymerization

Carcinogenic Substances (appendix IV) Defined in Appendix IV

>0.0005

Odours

283

Cf. authority decree Defined in Appendix IV B >0.002 Cf. authority decree Defined in Appendix IV A >0.005 Cf. authority decree Defined in Appendix IV D >0.025 Cf. authority decree No general case (see the aut horization authority decree)

Only special cases

1. See also carcinogenic substances category (Appendix IV). 2. These figures represent average monthly values.

Liquid fuel: 20 mg/m^ for the 10 metals as a whole and their compounds Residual content in vinyl chloride before drying: PVC = 50 mg/kg of polymer; dis persed homopolymers = 100 mg/kg of poly mer; dispersed copoly mers = 400 mg/kg of micro suspended and emulsified polymers; dispersed homopoly mers = 1,200 mg/kg of polymers; dispersed copolymers = 1,500 mg/kg of polymer^

284

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