Skip to main content

Month: October 2022

How to do Projects Economic Evaluation – Example on How to Calculate DCFRR

Rifka Aisyah Leave a comment

In this post, I want to share how to do projects economic evaluation by using example. In this example, we will learn relationship between investment, sales, raw material cost, operating cost, to get the following parameters that usually used in projects economic evaluation:

  • Net cash flow
  • Cumulative cash flow
  • Discounted cash flow

Example on How to do Projects Economic Evaluation

It is proposed to build a plant to produce a new product. The estimated investment required is 12.5 million dollars and the timing of the investment will be:

  • Year 1    1.0 million (design costs)
  • Year 2    5.0 million (construction costs)
  • Year 3    5.0 million (construction costs)
  • Year 4    1.5 million (working capital)

Read More

How to Do Projects Economic Evaluation – A Simple Example

Rifka Aisyah Leave a comment

In this example, I want to show you a simple example on how to do projects economic evaluation. As mentioned previously, there are several parameters that can be used to do projects economic evaluation, such as:

  • Net present worth
  • Rate of return (ROR)
  • Discounted cash-flow rate of return
  • Pay-back time

In this example we will use ROR and pay-back time.

Example on How to Do Projects Economic Evaluation

A plant is producing 12,000 ton per year product. The overall yield is 70%, on a mass basis (kg of product per kg raw material). The raw material cost $12 per ton, and the product sells for $37 per ton. A process modification has been devised that will increase the yield to 75%. The additional investment required is $35,000, and the additional operating costs are negligible. Read More

How To Do Projects Economic Evaluation

Rifka Aisyah Leave a comment

In this post, I want to share how to do projects economic evaluation. In my experience, doing project economic evaluation is not always daily activities of process engineers. However, when I involved in feasibility study project, we need to do projects economic evaluation. Also in my own experiences, as process engineers focused on creating several alternatives of process configuration, our team from industrial engineers did the projects economic evaluation. However, it will not hurt to understand general idea of project economic evaluations 😊

Since investing in chemical plants is done to make money, a system for evaluating project economic is required. For small projects, the decision-making process can typically be simplified by comparing the capital and operating expenses of various processing methods and pieces of equipment. When choosing between large, complicated projects, especially when the projects differ significantly in scope, time frame, and product type, more advanced evaluation procedures and economic factors are required. In this part, some of the more popular methods of economic analysis and the standards by which economic performance is evaluated are described. Read More

Preliminary Sizing of Cyclones

Rifka Aisyah Leave a comment

In this post, I want to share how to do preliminary sizing of cyclones.

Cyclone is the most common and effective gas-solids separator that uses centrifugal force. They can be constructed from a variety of materials, are generally simple structures, and can be designed to operate at high temperatures and pressures.

The reverse-flow cyclone is the most common design. In a reverse-flow cyclone, the gas enters the top chamber tangentially, spirals down to the conical section’s apex, and then moves up in a second spiral with a lower diameter before leaving through a central vertical pipe at the top. The solids travel radially to the walls, down the walls, and then are gathered at the bottom. Read More

Preliminary Sizing of Hydrocyclones

Rifka Aisyah Leave a comment

In this post, I want to share how to do preliminary sizing of hydrocyclones. In previous post, hydrocyclones are utilized for solid-liquid separations. The centrifugal force is produced by the motion of the liquid in this centrifugal device, which has a stationary wall. Like a gas cyclone, the gas cyclone operates on much the same principles. Hydrocyclones are inexpensive, reliable separators that work with particle sizes ranging from 4 to 500 micron. Figure below shows hydrocyclones typical proportion geometry.

Hydrocyclone typical proportion
Hydrocyclone typical proportion

Read More

Basic Sizing Equation for Sedimentation Centrifuges

Rifka Aisyah Leave a comment

In this post, I want to share basic sizing equation for sedimentation centrifuges. Based on previous post, sedimentation centrifuges used to separate materials based on the density difference between the solid and liquid phases. They are usually used to produce cleared liquid.

Basic sizing equation for sedimentation centrifuges use the term sigma (Σ). The sigma is used to describe a performance of a centrifuge regardless of the physical characteristics of solid-fluid system. The sigma value is equivalent to the cross-sectional area of a gravity settling tank with the same clearing capacity. The sigma value is often expressed in cm2.

The sigma theory is a description of how centrifuge performance is described. It offers a way to compare sedimentation centrifuge performance and to scale up from laboratory and pilot scale experiments. Read More