All BR&E Blogs

With changing EPA regulations in OOOOb, OOOOc, and Subpart W, it is of utmost importance for operators to accurately predict emissions from produced water storage tanks. To properly estimate storage tank emissions, the fluids entering the tank batteries must be well characterized – with known hydrocarbon and salt content. ProMax® is the perfect tool to help characterize the storage tank feeds and estimate emissions at different conditions.

Vent system sizes based on nominal, daily production may be inadequate. The flow of oil through the equipment at a wellsite facility is not always continuous, and a Peak Flow occurs during times that dump/throttle valves are open. The OOOOa rule requires certification that vent systems in place on wells constructed, modified, or reconstructed after September 18, 2015 are suitable to handle the peak flow of the facility.

For those unfamiliar with the rule, NSPS OOOOa is an amendment to the original OOOO (“Quad-Oh”) regulation governing air emissions from oil and gas production facilities. It affects well facilities constructed, modified, or reconstructed after September 18, 2015 and has a compliance deadline of August 31, 2017. This means every well drilled, fracked, or refracked after this date must be in compliance.

ProMax® offers a number of stream Analyses that can be applied to any stream in a simulation. The Line Sizing Analysis calculates either the minimum diameter that meets the pressure drop specification or the pressure drop for a fixed pipe diameter.

ProMax® offers a multitude of options for reporting information from a simulation. Callouts, Property Tables, and Property Stencils display values on flowsheets within a model, the Scenario Tool® can run numerous cases automatically and present the results in an Excel workbook, and the Report Button can create external reports in various formats - including Word documents and Excel spreadsheets. One additional, extremely powerful reporting tool is a User Defined Report Template, which allows for the construction of completely customized Excel reports.

Liquefying natural gas efficiently requires complex design, complex operation, or both. The process must cool, condense, and subcool a multicomponent mixture across an enormous temperature range. In the case of the classical cascade refrigeration, the refrigerants are relatively simple, but the multiple interconnected refrigeration loops are not. With a mixed refrigerant system, the roles are reversed. The equipment is relatively simple, as shown in Figure 1, but the complexity has been moved to the refrigerant mixture.

Each object inside of a ProMax model is readily accessible to external programs. In essence, anything that can be accessed with the keyboard and mouse through the user interface can be accessed through simple programming commands (think stream, property, unit operation, etc.). And this is done without the need of any add-ons to the program. ProMax is just built that way!

ProMax is structured in an open manner that makes it relatively straightforward to harness its various capabilities using simple programming commands. With minimal coding, it is possible to integrate ProMax calculations into other programs, or to create stand-alone gadgets that wrap only the needed portions of ProMax into a simple interface.

The design and optimization of separation processes is carried out using process simulators which utilize various calculation approaches. ProMax® 4.0 now has both the Ideal Stage method and the Mass + Heat Transfer method available for use in reactive and non-reactive systems. This blog will discuss some basic settings for use of the Mass + Heat Transfer model as implemented in ProMax.

To perform the characterization of a crude oil or petroleum fraction, the conventional approach is to split the feed into a discrete number of Oil Cuts (pseudo-components), based on a measured property, typically boiling point. This approach works well for the simulation of separation units where no chemical reaction occurs. However, in refinery reactors such as diesel hydrotreaters, catalytic reformers, and hydrocracking units, the use of conventional oil cuts is no longer applicable as they lack the necessary chemical information to properly characterize the large number of reactions.

The ProMax Scenario Tool® is an incredibly powerful tool that allows you to run multiple cases automatically within ProMax. This tool can be used to report results for multiple existing cases at differing conditions or for sensitivity studies to help you understand how process upsets will affect process performance.

The ProMax Depressurization Tool is available to calculate the temperature, pressure, and mass flow rate profile for a vessel that is venting, including heat input cases, such as an external fire. It is designed to assist you with several related scenarios, and to provide you with information on the venting and non-vented material compositions.

There are many scenarios that can lead to a dangerous increase in the pressure of a vessel. Fundamentally, the cause of increased pressure is due to unexpected mass or heat input, such as an external plant fire. In many cases, the increase in pressure may happen very quickly, so a properly designed and sized emergency depressurization system is necessary, typically in addition to the over-pressurization relief valves on the units. Here we discuss some basics on sizing the depressurization system, and effects that a fire may have on both wetted and non-wetted surfaces.

Properly sized relief valves provide protection to equipment during events where increased vessel pressure may cause damage, while also avoiding issues with excessive flow rates. Many scenarios can result in an increased vessel pressure, including: a run-away reaction, a loss of cooling, thermal expansion of a liquid, or an external fire. ProMax includes a Relief Valve Sizing Analysis to help you calculate the required area for many of these scenarios. This discussion examines specifying the ProMax Analysis, including what valves are available, the Standards available, how to set the relief conditions, and how ProMax calculates the area required for the different flow types that may occur during the relief conditions.

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Predictions of phase equilibrium in hydrocarbon systems require proper descriptions of the inlet composition and constituent components. When working with GC analyses for hydrocarbon liquids, it is not enough to simply use a normal alkane to describe the variety of species that may share the same carbon number. Hypothetical or “pseudocomponents” are required, described using their molecular weight and gravity, to ensure accurate and consistent results from flash separations as well as working and breathing losses.

Accurate predictions of atmospheric tank flash emissions depend on high quality thermodynamic properties and calculation methods as can be found in ProMax. They also require high quality laboratory analyses of pressurized liquid samples. To check the validity of these analyzed compositions, please make sure to compare measured temperature from the pressurized separator with the bubble point temperature calculated in ProMax. If the bubble point is higher than the measured separator temperature, then emissions will be under-predicted.

ProMax offers a large selection of variables that can be specified by the user, and for anybody new to simulation software this freedom can be quite daunting. How do you know which ones to set manually and which are better left for the program to calculate? Here are some tips to help get you started:

The short answer is NO. Although the ASTM D323 standard calls it an "absolute pressure", the value is in fact a gauge pressure. This blog will provide information to help you understand why.

The Property Input property stencil allows the user to display and change an input property directly on the stencil. The variable may be almost any user-definable variable in ProMax, including flow rates, temperatures, energy rates, and even User Defined Variables.

To model a brine solution in ProMax, the acids and bases comprising the salts must be entered along with water, and the Electrolytic ELR property package must be used. In the Electrolytic Property Packages the acids and bases dissociate to form the ionic species, and the salt concentration can be viewed by adding an Ionic Info Analysis...

The ProMax Tank Losses stencil is used to estimate the rate and composition of volatile losses from a liquid storage tank. Flashing, working, breathing, and loading losses are considered. The estimation is based on ProMax thermodynamics and the Environmental Protection Agency’s AP-42 methodology.

The Mach number is a dimensionless quantity representing the ratio of the actual fluid velocity to its speed of sound. Have you ever needed to calculate the Mach number in your pipeline simulations? In ProMax you can use the property calculator called Pipeline Mach Example to display the maximum fluid Mach number in your Flowsheet...

If you are modeling an amine unit with SO2 in the feed, possibly from flue gas which contained sulfur compounds before incineration, you might notice that the Recycle block fails to converge. This is due to the build-up of non-regenerable salts in the amine loop. Once in the system the SO2 forms heat-stable salts with the amine and has no way to escape. The amine will eventually be rendered ineffective by being tied up as a salt...

General tips for how to model liquid-liquid amine treaters, including general design hints and concepts, and also how to model a liquid treater in ProMax.

ProMax utilizes a Make-up/Blow-down block for many open-loop systems to keep the process in an accurate steady-state condition. These processes have losses of the circulating liquid through solubility and/or entrainment, and the losses must be recovered by adding additional solution over time. Utilizing the Make-up/Blow-down block allows ProMax to easily maintain a heat and material balance on the system, and for your circulation rate to be maintained at a desired flow rate without requiring you to calculate any losses in the process yourself.

If a ProMax file with an embedded Excel sheet is excessively slow to open, it may be caused by a tool from Microsoft that validates Excel files during loading. Microsoft has implemented a file validation add-in causing this. The longest validation delays appear to occur with files stored on a network location.

ProMax can rate many types of exchanger, including fin-fan exchangers, but to do so the exchanger must be either a two-sided or multi-sided cross-exchanger. However, when utilizing the fin-fan shape included with ProMax, you are limited to a single-sided exchanger shape. This does not preclude you from being able to rate the air cooler and use the fin-fan shape, it just means that you must use two single-sided exchangers connected together by a common energy stream.

ProMax has several options for generating reports on a project. The most commonly utilized versions are Word and Excel formatted reports, each with natural advantages.

BR&E recommends modeling a TEG contactor using ideal stages based on an overall column efficiency of 25-30% as stated in GPSA Engineering Data Book and other references. The 25% value is normally used so as to be on the conservative side. Thus an 8 tray contactor would be modeled as 2 ideal stages.

Utilizing Simple Specifiers and Solvers in ProMax can be of great benefit and provide much flexibility to the user. Specifiers and Solvers are calculators that enable the specification or calculation of properties and conditions in an indirect manner.

Some helpful hints on how to get your distillation columns to solve in most cases.

Here's a quick way to estimate approximately how much reboiler duty is being used to heat the rich amine stream compared to how much is used for the acid gas desorption reaction.

If your column in ProMax is not iterating when you press the execute button, here are some of the most common things that may be occurring to help guide you to what's happening in your case.

Calculating a rich approach is a useful way to find a suitable circulation rate for your solvent. If the approach to equilibrium is too high, a system upset is much more likely, and if it is too low, there is a chance of the solvent being overcirculated. This entry gives some additional information on how this variable is calculated, and how it can help you find an optimized flow rate.

A summary of what to do if too much or too little acid gases appear to be absorbed by the model, if the absorber or regenerator fail to converge, or if the recycle fails to converge in an amine unit simulation.

In 2006 Bryan Research & Engineering, LLC and Crosstex Energy Services, L.P. published an article for Hydrocarbon Engineering titled “Steady-State Simulators are Developing a Dynamic Personality.” This article helps step through one case of designing a ProMax simulation utilizing our Scenario Tool to model changing conditions, and finding an optimum operating condition.

Process engineers often express concern about amine reboiler temperatures being high enough to cause thermal degradation of the amine. However, thermal degradation is generally not a concern in amine reboilers heated with steam or heat transfer fluids.

When modeling crude distillation columns, boiling point curve temperature specifications are often used to characterize products (e.g. ASTM D86 90 Volume % Cut Point Temperature). In the early stages of the model development it may be easier to monitor the product boiling point curve temperatures rather than converge on a particular specification.

Water content is important for predicting freeze conditions, including hydrate formation, as well as corrosion in the plants. This is especially true in units containing H2S and CO2 as these tend to exacerbate these issues.

Why does the actual volumetric flow rate in ProMax not equal the standard liquid volumetric flow rate if the stream temperature and pressure are at standard conditions? The only time the actual and standard liquid volumetric flow rates will be equal at standard conditions is if the system forms an ideal solution. Solutions that are not ideal can have significantly different actual and standard liquid densities. The actual density of the liquid is computed using the user selected liquid density model in the ProMax environment. This is normally either the COSTALD or the Rackett model. The predictions from these models are mixture densities which include a volume change on mixing effect...

The Options.xml file specifies ProMax program defaults such as stream properties, units sets, items appearing in Tooltips, etc. Some default settings can be changed using Project Options, however, extensive changes may be inconvenient if they are to be performed for each new Project. Other default settings cannot be accessed through the ProMax program. By editing the Options.xml file, default settings can be specified such that each new Project will use these modified default settings. Examples...

Recovery values are very useful to see on a process flowsheet. However, sometimes you may want to display these values with a custom name. Let us say you want to see the elemental sulfur recovery for a Claus unit. There is a simple way to display this value as described in another blog entry.

Have you ever needed to add a solver to your simulation that could calculate exchanger temperature change to achieve an Approach Temperature or End Point UA? The ProMax Property Stencil Add-in offers what is known as a UA Wizard that will achieve the same results as a solver.

There have been many questions concerning temperature rises predicted by ProMax across JT valves and other adiabatic flashes. Depending on conditions, ProMax may predict the temperature to rise in the flash. I have created a document that explains the cause of this temperature rise and mathematically proves its existence for simple systems.

Amine systems can be tough to calculate. However, there are a few things that you can do to help out. In this post we're going to discuss a few options on the convergence tab, especially the Enthalpy Model and the Inner Loop Model.

What seems like an insignificant amount of ammonia in the sour feed gas to an amine unit can be detrimental to the sweetening process. Ammonia in an amine sweetening system can cause reduced absorption of acid gas, as well as greatly increased stripper condenser and reboiler duties due to build up of NH3 in the system.

The Relief Valve Sizing Analysis in ProMax calculates the Effective Discharge Area, Relief Pressure, and other parameters. This analysis reports estimation of latent heat of vaporization for mixtures (Inlet Latent Heat parameter) which may be used for other applications.

If you are trying to find the water content or water dew point of your gas, add a “Freeze Out, Hydrate, H2O Dew Point” analysis to the stream. The temperature of the water dew point is given, as is the water content of that stream (reported as lbm/MMSCF, pounds per million standard cubic feet).

ProMax uses the arithmetic average method for calculating mixed liquid viscosity because that method is used by all of the pipeline pressure drop models included in the program (see Brill and Beggs, 1991) except the OLGAS correlations. However, the viscosity of oil/water mixtures is extremely difficult to predict.

The Property Stencil distributed with ProMax 2.0 includes tools such as Copy Stream Conditions, Flow Duplicator Example, Property Calculator, Cn+ GPM Calculator, Cn+ GPM Solver Example, UA Wizard, and many others.

The 2.0 version of ProMax includes energy budget and recovery calculation objects that are fully customizable by the user. The recovery objects provide a summary of the project inlets, outlets, losses (due to convergence tolerances), and component relative outlet recoveries.

Plug flow reactors in ProMax can be used to model tubular flow reactors in which there is no mixing in the horizontal direction and perfect mixing in the radial direction. Kinetic information must be known and the reaction does not have to come to equilibrium.

Like the Gibbs Minimization reactor, the Equilibrium reactor in ProMax also calculates chemical equilibrium. However for this reactor stoichiometric equation information must be entered by completing the data for a Reaction Set.

The Gibbs Minimization reactor in ProMax has the advantage that stoichiometric equations are not required. Equilibrium is determined from the free energy and the heat of reaction is calculated automatically.

When entering components in ProMax, the components may be filtered based on chemical formula. If the exact formula is known, you may enter the formula in the field and all compounds matching that formula will be listed, subject to other filters.

In ProMax, color indicates the status of blocks and streams. For the user with normal vision, a red block is unconnected, a blue block is unsolved, an orange block has an approximate solution, and a green block is solved.

New in ProMax 2.0 is the ability to create User Value objects which are values or properties defined by the user. Related User Value objects are grouped into User Value Sets as defined by the user.

Multi-Sided or "Complex" Heat Exchangers are brazed aluminum plate and fin exchangers which can heat and cool up to 15 fluids simultaneously. They are commonly used in cryogenic service, both in air liquefaction and in high efficiency gas processing plants.

In a Claus Sulfur Recovery Unit, COS and CS2 are formed in the acid gas burner and are partially destroyed in the first Claus bed (provided the appropriate catalyst is present and the temperature is sufficiently high). Equilibrium models do not adequately predict the formation of COS and/or CS2 in the burner as observed concentrations can be significantly higher than equilibrium predictions.

The typical Claus sulfur recovery unit includes an acid gas burner, a waste heat boiler, and sulfur condenser followed by 2, 3, or 4 catalyst bed converters for conversion of H2S and SO2 to sulfur. Each converter is preceded by a reheater and followed by a sulfur condenser.

ProMax gives its users great flexibility when designing complex towers with sidedraws and side reboilers. There are several ways to represent side draws and the user should understand the differences within the options given in ProMax.

Reactor specifications vary depending on the Reactor Type, Reactor Configuration, and whether or not the Reactor is adiabatic. All Reactors require some specifications in the Reactor block dialog.

Depending on composition and pressure, multiple hydrate, water freeze out, or CO2 freeze out temperatures are possible. ProMax calculates up to three of these points. When only a single point is present, the solid is stable at all temperatures below that point.

One convenient feature in ProMax is the “What’s This?” help. You can get quick information on almost any parameter without having to access the main Help file.

The Vapor Pressure Analysis in ProMax returns values for both Reid and True vapor pressures. The calculated True Vapor Pressure of the stream is based on ASTM D2889-95a(2000) Standard Test Method for Calculation of True Vapor Pressures of Petroleum Distillate Fuels.

ProMax includes a number of aliases for many of the available components. Depending on the Classification used when selecting components, a single compound might be named in different ways.

There has been a question concerning the temperature coming out of the rich amine flash in ProMax. Often when a higher pressure liquid stream is flashed to a lower pressure some vapor is generated and some cooling occurs, however, this is not always the case.

There are several definitions of trayed column flooding, and a number of correlations used to calculate flooding. Fraction Flooding in ProMax is calculated by Fair’s correlation which is generally conservative and includes both jet and downcomer flood data in its development.

Ammonia present in the rich feed to an amine stripper, even in the ppm range, tends to build up in the upper section of the stripper between the condenser and the rich amine feed leading to operating problems. Simulators such as ProMax which can model amine units reflect the operational problems as difficult convergence of the stripper.

When setting up the specifications for a distillation column with a partial condenser and reboiler, the one item that most people in operations can tell you is the temperature in both the condenser and reboiler. This, however, is not necessarily the best information to use as the initial guesses in setting up a simulated distillation column.

Kohl (1997) contains excellent information concerning trayed vs. packed columns for gas treating applications. Some information you will find in this text includes the following:

ProMax includes an extensive library of examples to aid the user in setting up a plant model. It is much simpler to start with an example and modify the inlet conditions and equipment operating parameters than it is to start a model from scratch.

A number of correlations are available for predicting pressure drop and liquid holdup in multiphase flow through a pipeline. None of the available correlations is 100% accurate.

The 2.0 Version of ProMax includes a number of multiphase flow correlations in addition to the original Correlations included in the 1.2 Version. The original correlations were: Beggs and Brill, Dukler et al, Duns & Ros, and Orkiszewski.

Although you can model any column (for example an amine absorber) using real stages, ideal stages are recommended because the column executes much faster and calculations are much more stable. If you are designing an amine unit, you should ALWAYS use ideal stages in the absorbers and strippers rather than real stages.

When ProMax performs the freeze-out analysis calculations for a stream with a very low water content (e.g. dehydrated natural gas), the water dew point may not be calculated or the value may not be meaningful. In most cases a liquid water phase will not form, or will not be thermodynamically stable for the current conditions.

Part Per …. Dallas? Some people get so caught up with the specifications that are handed to them or expected of their plants that they lose track of what they really mean. There is very little to put these numbers to a scale that can be really understood.

In certain cases there may be two hydrocarbon dew points as shown in the phase envelope below for a pressure of 1000 psia. The Dew Point Temperature reported by the Vapor Pressure Analysis in ProMax may not always be the highest dew point.

Bryan Research and Engineering’s (BR&E’s) ProMax simulation software provides the user with ultimate flexibility in the use of measurement units. While several default unit sets are available for the operator to choose as his global preference, each individual Process Stream, Energy Stream or Unit Operation can be individually customized to mix and match units to meet the project requirements.

One area where ProMax is getting a lot of attention is in Coal Gasification or IGCC processes. Since IGCC involves partial oxidation rather than complete oxidation, the organically-bound sulfur is mainly converted to H2S rather than SO2.

Physical solvents are becoming increasingly popular as gas treating solvents, especially for coal gasification applications. ProMax accurately models a number of physical solvents such as DEPG (Coastal AGR), NMP or N-Methyl-2-Pyrrolidone (formerly Purisol), methanol (Rectisol), and others.

Probably the most significant difference between ProMax and other amine sweetening simulators is that the ProMax Electrolytic ELR package uses the TSWEET Kinetic Model to predict the absorption of CO2 by amines.

All amine sweetening models are different, even if they have the same name or start with the same basic equation. The models may be based on different criteria: correlations, mass transfer, equilibrium with efficiencies, etc.

The ProMax simulation software allows the User to develop a predictive model that can let you know how a processing plant will respond to changing conditions. While still a steady-state model, ProMax performs iterative calculations, rating and adjusting equipment performance within each iteration, until convergence is achieved.

Interest in simulating caustic treating processes for removal of acid gas from both vapor and liquid hydrocarbon streams has increased significantly. ProMax can accurately predict the absorption of acid gas compounds and sulfur species such as CO2, H2S, and mercaptans from liquid or vapor streams by caustic (NaOH) solutions.

The most common use for a Propagation Terminal in ProMax® is in a propane refrigeration loop, where the duty required by a Heat Exchanger or Process Chiller(s) is used to determine the flow rate of the refrigerant within the loop. Since this calculated flowrate will be propagated in both an upstream as well as downstream direction, at some point in the loop blocks will have composition and flowrate sent into it from both directions, which is flagged as an error even though the two values are identical.

In today’s high speed world, the typical Process Engineer does not have the opportunity to work with his process simulation tools on a daily basis. Because of this, it is often difficult for the engineer to remain up to date and proficient in the use of this most important tool.