Showing papers in "Hydrocarbon Process in 1987"

Cumene by catalytic distillation

Abstract: The novel concept of Catalytic Distillation has been commercialized in the CRandL MTBE process, in which combined reaction and distillation provide energy savings over conventional processes This concept has now been extended to production of cumene from benzene and propylene In this case the advantages of the technique are not only energy savings but significant reductions in by-product losses and capital requirements In this paper the development of the process is discussed and the economics of commercial operation are presented

Predicting flash and pour points

Abstract: Flash point is correlated with ASTM 10% temperature. Pour point is correlated with molecular weight, specific gravity and kinematic viscosity at 100/sup 0/F. The flash point method was tested over an ASTM 10% temperature range of about 400 to 900/sup 0/F. The correlation for pour points is applicable to fractions with molecular weights of 140 to 800 and viscosities of 1 to 3,500 cSt.

Computer control improves ethylene plant operation

Abstract: ICIA Australia ordered a turnkey 250,000-tpy ethylene plant to be built at the Botany site, Sydney, Australia. Following a feasibility study, an additional order was placed for a process computer system for advanced process control and optimization. This article gives a broad outline of the process computer tasks, how the tasks were implemented, what problems were met, what lessons were learned and what results were achieved.

Save by absorption heat pumping

Abstract: The author compares absorption heat pumping (AHP) to mechanical vapor compressor (MVC) heat pumping. The moving part of the AHP is a pump easy to maintain and inexpensive to spare. The mechanical component of the MVC is a vapor compressor which requires more maintenance and is cost-prohibitive to spare. Also, in the MVC system, a purified product stream is heat pumped in an open compressor, thus risking product contamination. In the AHP system, the cold and hot utilities are heat pumped. Therefore, product integrity with an AHP system is well protected as in a conventional fractionation column.

A new process to make oxo-feed

Abstract: An oxo-synthesis process uses a feed mixture of hydrogen and carbon monoxide that is typically in a ratio of 1:1 (H/sub 2//CO). Commonly, the oxo-process feed is made from reformers which give a much greater hydrogen ratio. But this new process makes the right H/sub 2//CO ratio directly from the reformer step. The flow diagram for the process is shown. Suitable feeds include: natural gas, LPG, methanol or related hydrocarbons. A mixture of the feed with steam and CO/sub 2/ enters the reformer where the feed mixture is converted to a product mixture of H/sub 2/, CO, CO/sub 2/ and H/sub 2/O in the presence of newly developed catalysts. Both the product mixture and hot flue gas from the reformer pass through separate waste heat boilers, coolers and CO/sub 2/ absorbers. Both absorbers use a recycled MEA solution to absorb CO/sub 2/. The CO/sub 2/ loaded MEA solution is stripped of CO/sub 2/ via a stripper and reboiler before returning to the absorbers. The recovered CO/sub 2/ supplies the needs of the reformer feed.

Alloys for ethylene cracking furnace tubes

Abstract: The selection of appropriate metallurgy for pyrolysis furnaces is keyed to the following important considerations: Oxidation; Carburization; Creep strength; High temperature ductility; Cost. There are many good foundries throughout the world that offer a spectrum of products, including their own proprietary formulations, that address each of the above requirements. Unfortunately there is no simple assessment of properties that ensures maximum cost-effectiveness for the life of the unit. In addition, the combination of heat to heat variations and unanticipated service conditions make life prediction difficult. Over the past 25 years, and particularly in the last 10 years, there have been significant improvements in the properties of cast high temperature stainless alloys through careful control of chemical composition. This review examines the developments in the light of the requirements and provides a synopsis of the state of the art in pyrolysis tube metallurgy.

How flow dispersion affects exchanger performance

Abstract: The Fluid Dynamics of the two streams in heat exchangers have not been analyzed sufficiently for studies of pressure drop. While the effect of axial dispersion of the process stream on the driving force is generally considered in the design of mass transfer operations, it is ignored for the design of the heat transmitting area. There may exist, however, large differences in heat exchanger efficiency as a result of different flow patterns, which may lie between perfect mixing and plug flow. In general, the heat transfer characteristics of different types of heat exchangers, e.g., single pass, cross flow, shell and tube, are represented by the correction factor F = Q/sub T//UA..delta..T/sub iotan/ or the heat exchanger effectiveness E = Q/sub T//((mc/sub p/)min (T/sub in/ - t/sub in/). Graphical representations are generally given for plug flow and perfect mixing and are used to obtain the heat transfer, transfer area and the fluid outlet temperatures. In reality, however, neither of the extremes, plug or perfect mixing, are to be expected. The flow patterns will be of an intermediate type. In this article, graphical representations are given for this situation in terms of the factor, E, whose application is recommended when outlet temperaturesmore » are to be calculated.« less

Gas treaters need clean amines

Abstract: Alkanolamines are used in the HPI to remove hydrogen sulfide (H/sub 2/S) and carbon dioxide (CO/sub 2/) from gaseous streams When the amine solution becomes dirty, operating costs increase Then granular activated carbon can be used to clean up the dirty amine and restore effective amine treating For example, the use of granular activated carbon at a 40 Mbpd refinery reduced amine system operating costs by $205,800 This article describes the system

FCC's effect on refinery yields

Abstract: For planning and optimizing an integrated refinery operation, a flowsheet system based on simulation technology has many advantages. Case studies using such a simulation system are presented to show the effect of changing FCC unit operations on the refinery scheme. The studies look first at the effect of switching to an octane catalyst and then at the effect of using a deep vacuum cut point for the feed. The article concludes that the refinery-wide simulation program is easy to use because it generates its own process performance information. Only crude assay data are needed. A major benefit of the system is that it can identify opportunities with considerable commercial benefit in today's competitive and changeable oil refining industry.

Avoid heat transfer equipment vibration

Abstract: Tube bundles in heat exchangers, boilers, superheaters and heaters are often subject to vibration and noise problems. Vibration can lead to tube thinning and wear, resulting in tube failures. Excessive noise can be a problem to plant operating personnel. Large gas pressure drop across the equipment is also a side effect, which results in large operating costs. With the design checks presented in this paper, one can predict during design if problems associated with noise and vibration are likely to occur in petroleum refineries.

Program designs and prices vessels

Abstract: A computer program is presented that combines ASME Section VIII, Division 1 pressure vessel design with several cost correlations into a package most engineers should find useful. Cost and weight of the vessel and internals such as trays, packing, demisters, lining and supports are computed. Provisions for insulation and different materials of construction for the vessel have been built into the program. Costs can be kept current through the use of a popular chemical engineering index. Copies of this program can be obtained at no charge. A sample output is illustrated. Any vessel design covered by ASME UG-27 and UA-2 code (thin-walled or thick-walled equations) can be used. ''Typical'' values are given for most input variables to aid the user. The user can also call up convenient reference tables for maximum allowable stress, welded joint efficiency, packing prices, packing weights, internals and vessel linings. Multiple cases can be run using screen results for sensitivity evaluations prior to printing a hard copy report. The program is written in Microsoft BASIC for the IBM personal computer and compatible machines. Adaptations to other computers using similar BASIC languages are possible. The main program is about 270 lines long and occupies less than 31more » K bytes of memory (including user tables).« less

Incinerate your hazardous waste

Abstract: Incineration is becoming a major method for final disposal of hydrocarbon-processing byproducts in petroleum refineries. Incineration alters the form of the organic materials, combining them with oxygen in the air to produce harmless carbon dioxide and water vapor. Inorganics in the waste must be further treated to ensure they do not reach the surrounding air or water. But there are acceptable technologies to process these byproducts of combustion. Plant incinerators are being designed to handle the total load of organic waste from the HPI. These systems can safely convert the previously hazardous waste materials to safe compounds. Combined with central waste treating systems to treat large quantities of plant aqueous wastes, the plants can reduce the equations for hazardous discharges dramatically. Operating units already demonstrate the capability.

Reduce costs with knowledge-based maintenance

Abstract: Human psychology plays a major role in this situation. A repairman is employed to ''do maintenance.'' That's his job. Management evaluates his performance on how actively he goes about his work. In experience-based maintenance programs, repairmen are not employed to ''not do maintenance.'' It would be unthinkable to have idle repairmen even though the plant is operating perfectly well and needs no attention. People must work to earn their pay. Knowledge-based maintenance programs start with the management philosophy that doing maintenance is an unproductive and uneconomic activity. The goal is to have a 100 percent reliable plant that never needs any maintenance of any kind; not a single manhour during the life of the plant. Unfortunately, that is an unattainable goal. Plants can't operate without maintenance. Consequently, management's policy becomes one of identifying essential maintenance, doing that work, doing it well and eliminating or at least minimizing all other work. In an earlier paper, the author defined three kinds of maintenance work: essential, optional and luxury. The usual objective is to do the essential work and that part of the optional work that is economically beneficial. The uneconomical optional and luxury work are avoided. Knowledge-based maintenance programs are structured tomore » achieve these objectives.« less

Recent data on resid hydrocracker

Abstract: Amoco Oil's LC-Fining resid hydrocracker, which started up in December 1984, achieved near-design conditions in 1985 with resid feed being charged at an 81% service factor. The process and mechanical performances were outstanding, far exceeding expectations for initial performance. In April and for most of May 1986, the unit was shut down to remove bottlenecks in the downstream fractionation equipment - solid deposits had occurred. During this shutdown, the reactors were not entered and the catalyst remained in place. The resulting improvement in performance is demonstrated by the following range of catalyst performance data for the period of June-September, 1986: Avg 97,8% service factor; 88-95 wt % desulfurization; 96-97 wt % metals removal; 64-82 wt % Rams carbon conversion. Many of the world's heaviest crudes have been processed. There were no problems with carbonaceous deposits in the reactor fractionation section during the latter period. However, three very short but separate train resid outages were required in September, 1986, to remove salt deposits from the reactor effluent exchanger following a severe upset on the crude unit desalter. Additional improvements are anticipated.

Reducing exchanger fouling

Abstract: This article points out that fouling from hydrocarbon streams leads to enormous financial penalties in terms of additional energy consumption and debits in thruput. A typical 100,000 bpsd oil refinery might incur total fouling related expenses of around $10 million per annum. About half of this cost can be attributed to deposit formation in the network of heat exchangers used to preheat crude oil from storage conditions to around the 350/sup 0/C necessary for operating the crude distillation unit (CDU). An example preheat train is shown in Fig. 1. More than one category of fouling may be responsible for the overall deposition process. For example, the high inorganic contents of CDU preheat exchanger deposits suggest that crystallization, particulate, corrosion and hydrocarbon degradation mechanisms are all contributors. Inevitably, therefore, no single simple solution to the hydrocarbon fouling problem is available.

Exchanger design using disc and donut baffles

Abstract: Baffles Generally are used on the shell side of heat exchangers and reaction vessels to induce turbulence and thus increase shell side heat transfer coefficient. Baffles may be either segmental or disc and donut. Although by far the most common baffles are segmental, disc and donut baffles have certain advantages and find their unique applications in special heat exchangers and reactors.

How construction affects column control

Abstract: In development of control strategies for distillation columns and absorbers, generally no attention is paid to the construction parameters and the type of built-in trays of the column Industrial experiences show that this causes difficulties In the case of vapor flow manipulation, inverse concentration response may be obtained on trays with downcomers, while on trays without downcomers, controller tuning problems arise

Gaining operator acceptance of advanced controls

Abstract: Procedures that can help petroleum refinery control engineers efficiently and safely commission advanced computer controls are described. Tips on how to overcome successfully the operator's concerns about advanced controls, and how to prevent unit upsets during control commissioning are also provided. Probably the largest obstacle to implementing the first advanced controls in a plant is the operator's resistance to the new advanced control system and computers. Also, the control engineer must prevent a unit upset during the testing and commissioning of advanced controls. Before starting control commissioning, a control engineer should first understand the operations control house environment. This is important because he will be spending a lot of time in the control house during commissioning.

Calculating piping heat loss and insulation thickness

Abstract: This basic computer program evaluates, for an assumed length of pipe, the heat loss along with the average inside an outside wall temperatures, with and without insulation. The final fluid temperature can also be found. A comparison of capital cost for the insulation versus operating cost can also be drawn from the results of this program. Heat loss can be a costly problem when a superheated fluid travels a long distance. Under the worst conditions, condensation could occur which could restrict the fluid from being used for its intended purpose. In evaluating the heat loss, compare the final temperature of the pipe versus the pipe length during the worst conditions possible. If the fluid condenses before the end of the pipe piping insulation should be considered.

A better cooling water system

Abstract: To prepare their newly constructed reduced crude conversion (RCC) open recirculating cooling water system for the implementation of a corrosion and deposit control water treatment program, Ashland Petroleum, Catlettsburg, Ky., made plans for and carried out precleaning and passivation procedures. Here, the authors share the results, and some potential guidelines for one's own operations. Inspection of equipment after precleaning showed that the precleaning procedures was very effective in removing undesirable matter. After precleaning and passivation of the system, the recommended cooling water treatment program was started. Corrosion rates for mild steel specimens ranged from 0.5 to 1.5 mils per year (mpy), with an average of 1.0 mpy. The corrosion rates for admiralty specimens ranged from 0.1 to 0.2 mpy. Benefits of the precleaning and passivating programs greatly outweigh the costs, since the normal cooling water treatment program for corrosion and deposit control can then operate more effectively.

Optimizing exchanger design early

Abstract: It is not practical for process engineers and designers to make a rigorous economic evaluation for each component of a process due to the loss of time and money. But, it's very helpful and useful to have a method for a quick design evaluation of heat exchangers, considering their important contribution to the total fixed investment in a process plant. This article is devoted to this subject, and the authors present a method that has been proved in some design cases. Linking rigorous design procedures with a quick cost-estimation method provides a good technique for obtaining the right heat exchanger. The cost will be appropriate, sometimes not the lowest because of design restrictions, but a good approach to the optimum in an earlier process design stage. The authors intend to show the influence of the design variables in a shell and tube heat exchanger on capital investment, or conversely, taking into account the general limiting factors of the process such as thermodynamics, operability, corrosion, etc., and/or from the mechanical design of the calculated unit. The last is a special consideration for countries with no access to industrial technology or with difficulties in obtaining certain construction materials or equipment.

Predictive control enhances H-Oil hydrocracker operation

Abstract: Closed-loop reactor temperature control has been successfully implemented on a new ebullated-bed H-Oil hydrocracking unit, reducing temperature variations by 70%. The IDCOM process identification and control technique was chosen to accommodate difficult dynamics and to make the best use of multiple inputs. The near-integrative dynamic response characteristics of the lead reactors spurred an innovation in the IDCOM control structure to handle processes with extremely long response times. This paper describes the H-Oil process, the control objectives, the control strategies and the performance and benefits realized.

Increase profits from the FCCU

Abstract: The refinery unit from which the most revenue can be generated most easily is the fluid catalytic cracking unit (FCCU). This article offers a quick review of some ideas for increasing FCCU profitability. Too often, the natural inclination is to make as few changes as possible. Even then, much time and effort are spent to insure the changes will be successful. Yet the present economic environment will not tolerate very many time-consuming change-overs. Perhaps the following ideas will help guide you to successful unit improvements. These ideas are by no means all of the methods available for increasing FCCU profitability, but they are possibilities that should be considered: increasing feed rates; improving product quality, distribution, and recovery; and reducing energy consumption.

Impact of Rvp reduction

Abstract: Les scenarios d'approvisionnement/demande/fixation des prix des hydrocarbures sont rediscutes en fonction de l'evolution de la qualite de l'essence, notamment en ce qui concerne sa volatilite et son indice d'octane. L'influence sur les procedes de raffinage et la capacite de production des raffineries est examinee

Using densitometers in gas metering

Abstract: This article discusses how the densities of natural gases can be measured or predicted. It focuses on vibrating-element densitometers. The information demonstrates that the uncertainty of these densitometers may be as low as +- 0.1 percent if the instruments are calibrated accurately and if the densities measured are processed correctly. Equipment used to meter large flows of natural gas at high pressure must be designed to increasingly high accuracy standards. Today the uncertainty of volume flow measurement at laboratory test rigs is as low as 0.3 percent if gravimetric, volumetric or transfer standard techniques are used for calibration. Simply measuring the volume of gas that flows through a metering station is not sufficient for custody transfer, since the volume of gas delivered is billed at given reference conditions, whereas at the station the gas is measured at flowing conditions. The volume measured, therefore, must be corrected to normal or standard reference conditions.

Costs to transport natural gas

Abstract: Relative Economics are discussed for transporting natural gas by four ways: converting to LNG and using LNG tankers, as a gas using on-land and subsea pipelines, converting to methanol and using conventional tankers, and compressing and using tankers with pressurized containers. Distances and routes are important factors when determining cost. Specific examples are given for transportation between : Arabian Gulf and Europe, Africa and Europe, and Islands separated by short distances.

How new styrene unit is working

Abstract: A modern styrene unit will have utility requirements less than half of those for a 1940's unit. The byproduct formation will be less than a third. The process mechanism, steam dehydration of ethylbenzene, is primarily unchanged, but progressive improvements to the process make it a highly competitive system. Against this highly developed system, UOP and the Allied-Signal Engineered Materials Research Center developed some novel concepts and a catalyst to further improve the production of styrene. These were discovered and tested at the Research Center, and then demonstrated by Mitsubishi Petrochemical Co. (MPC), first in their laboratories at Yokkaichi, Japan, and later in a full-scale demonstration unit at Kashima, Japan.

Controlling processes with inverse response and dead time

Abstract: Model based control such as a Smith Predictor or a dynamic reconciliator has been applied successfully in control of systems with a major dead time. The purpose of the model-based control strategy is to eliminate the dead time and thus provide tight control. In 1984 a compensator for systems with an inverse response was proposed and this idea was used in control of systems with inverse response and a small dead time. In the latter case the compensator accounted for the inverse response although the small dead time was not eliminated. Some processes, however, show an inverse response and major dead time as well. This article proposes a technique for the compensation of both these effects. The technique has been successfully applied to temperature difference control of a chemical reactor.

HRSGs for gas turbine applications

Abstract: Waste heat recovery plays a dominant role in power and process plants Heat Recovery Steam Generators (HRSGs) are widely used to recover energy from waste gas streams either because of process considerations or for economic reasons HRSGs in sulfuric acid and hydrogen plants are examples of the former, while HRSGs in gas turbine installations and in incineration plants are examples of the latter This article outlines the features of HRSGs for gas turbine exhaust, which will be of interest to plant engineers and consultants