Jeferson Costa Chemical Process Engineer

01/07/2025

HOW NPSHa IS CALCULATED BY CHEMICAL PROCESS ENGINEERS IN PLANT DESIGN

The are 3 main information a chemical process engineer must defined for the correct quotation and purchase of a pump: rated flow, rated head and NPSHa. There is other relevant information to be informed in the datasheet, but let's focus on the NPSHa for this post.

In a few words, NPSHa is the pressure of the liquid at the pump suction minus the v***r pressure of the liquid at the operating temperature. The results of this calculation, plus a safety margin, must be higher than the NPSHr.

But how to define the pressure of the liquid at the pump suction?

Besides the source fluid composition, associated with pressure and temperature, leading to the fluid properties. The NPSHa is strongly influenced by the elevation of the fluid in relation to the pump suction. This elevation, by its hands, depends on the stage of the project.

At the Conceptual Design phase, there is no pump (project-specific curve of performance) information available. In many cases, vessel elevation is defined based on minimum values used by Design Companies. No plot plant or layout is available, so it is not possible to perform a detailed pressure drop calculation. NPSHa at this stage is an estimation.

In Basic Engineering, usually, the plot plant is available. This way, it is possible to have better information about the location of the vessel and the pump. Allowing the pressure drop calculation up to the pump suction. If any pump quotation is available, the vessel elevation is still preliminary. So the NPSHa is preliminary.

In the Detailing Engineering Phase, the pump curve for the project (vendor selection) is finally available. Based on that, the vessel elevation can be confirmed or will need to be revised to comply with the pump NPSHr. At this stage, it is possible to calculate the "final" NPSHa for the pump.

03/05/2025

LABOR DAY IN FRANCE 2025

Day off from and plant design to appreciate good moments with my beloved wife in the Parc de Seaux, France.

16/04/2025

SIZING HORIZONTAL VESSEL SEPARATORS WITH BOOT AS A CHEMICAL PROCESS ENGINEER

As a chemical engineer in plant design, you will deal with the sizing, selection, design and evaluation of equipment. Most often, the opportunity to perform these activities will depend on the type of company you are: Licensor, Designer, and Operator.

Vessel sizing is performed by the chemical process engineer in the initial steps of plant design and reviewed in the following steps until it is frozen for plant design purposes.

Today, let me share with you some 3 considerations for horizontal vessels separators with boot:

1) VERTICAL x HORIZONTAL
The first step is to define if a vessel should be vertical or horizontal. In general terms, vertical vessel are used where the amount of gas in the feed stream is higher than the liquid. So, the first check is to calculate the v***r fraction of feed stream, if below 0.5, select horizontal.

2) BOOT x WEIR
Boot and weir are used to make easier the segregation of high-density fluid from the light density fluid. In this sense, they will be considered in a vessel separator for 3 phase service (v***r/liquid/liquid) or 2 phase service (liquid/liquid). If you need to separate only v***r from liquid, boot and weir are not required.

In general, boot are selected when the amount of heavier liquid is small compared to the lighter liquid. As a rule of thumb, if the ratio between heavier/lighter volume is below 10%, use boot.

3) BOOT DESIGN RESTRICTIONS
As boot leads to modification of the cylindrical part of the horizontal separator, some restrictions should be considered.

First, boot diameter should not exceed 1/3 diameter of the horizontal vessel. Second, the boot height should not be higher than the vessel diameter and third, for small diameter size, boot internal diameter is defined based on standard pipe size, usually between 8" and 24".

Deviations from these restrictions should be evaluated case by case.

QUIZ
Why are vortex breakers added only to liquid withdrawal nozzles?

21/12/2024

WHAT MATTERS TO START AS A CHEMICAL ENGINEER IN PLANT DESIGN

Plant design is the most fascinating field of expertise for a chemical engineer at my point of view. It is in plant design new industrial plants are developed and starts getting life.

Each activity in this field has the purpose the allow the purchase of equipment, control valves, intrumentation and so on, as well as, permit the safe and efficient operation of the plant.

Doing plant design is much more than doing calculations or process simulation. Doing plant design as a chemical engineer starts with knowing that all deliverables and activities you perform has a bigger goal, solve a problem.

The problem can be reach a new product specification, expand company's market, improve operation efficiency, increase businness revenews, and much more.

Based on that, sooner you build your engineering sense to solve problem as a chemical engineer, better will be your conversation and chances to get a job in plant design. Faster will be your develoment and recognition.

To prepare the chemical engineer ahead of all calculations in plant design, the new version of Inprocess Booster, starts building the fundation for boosting chemical engineering and plant design knowlege.

If you wanna know more about chemical engineer's roles and responsibility in plant design follow my profile 😄

QUIZ
What differs a junior engineer from a senior engineer's?



Picture: Inprocess Booster+ training

29/11/2024

THE ROAD MAP FOR PLANT DESIGN JOBS

The Last episode of the Chemical Engineering Design Week is already available. Now, it is time to get access to the road map to become a skilled and confident chemical engineer for plant design jobs

https://youtu.be/eWn_okrV1PU

CHEMICAL ENGINEERING DESIGN WEEK - 100% FREE ONLINEGet the material at https://inprocessbooster.com/engineeringweek_orgIt is your time to become a chemical e...

29/11/2024

TOP SKILLS FOR CHEMICAL ENGINEERS get a job in plant design

Source:
https://youtu.be/V4HHsYego7c

CHEMICAL ENGINEERING DESIGN WEEK - 100% FREE ONLINECourse material at https://inprocessbooster.com/engineeringweek_orgIt is time for your chemical engineerin...

27/11/2024

HOW TO START AS A CHEMICAL ENGINEER IN PLANT DESIGN

Episode 1 of the Chemical Engineering Design Week is already available. There, I will share with you the best way to start your career as a chemical engineer in plant design.






Source:

CHEMICAL ENGINEERING DESIGN WEEK - 100% FREE ONLINEGet the material at https://inprocessbooster.com/engineeringweek_orgIt is time for your chemical engineeri...