Process Engineering

“Process design is the lifeblood of chemical engineering,” says Dr. Ravi Randhava, President of Unitel Technologies. “It’s all about using science and experience to develop and optimize the ‘best’ method to transform incoming feedstocks into higher value products.”

Unitel’s principals have been involved in hundreds of first-of-its-kind projects for 40+ years for customers around the world. “Yes, we always start with proven chemical engineering fundamentals. But then we add experience, heuristics, intuition, computer simulation, and a ‘never-say-die’ attitude into the equation,” he adds. “It’s been a win-win formula that has enabled us to successfully work on assignments that many of our friends in the industry have shied away from.”

The standard practice of process engineering at Unitel involves the preparation of three types of documents:

  • Conceptual engineering with block flow diagrams (BFDs) that represent the overall process, with basic kinetics, equilibrium and thermodynamics and AACE Class 5 cost estimates.
  • Basic engineering and design: process simulations, process flow diagrams (PFDs), material and energy balances, process optimization, front end engineering and design (FEED) studies, major equipment layout (2D or 3D) and AACE Class 4 or Class 3 cost estimates.
  • Detailed engineering and design: piping and instrumentation diagrams (P&IDs), equipment and instrument data sheets, detailed bills of materials (BOMs) including recommended manufacturers and model numbers, line size and valve calculations, system visuals (2D or 3D drawings), electrical engineering and control system logic, AACE Class 3 or Class 2 cost estimates, and a “ready-to-bid” or “ready-to-build” design package.


Unitel makes extensive use of the ASPEN and HYSYS platforms for its computer simulation activities.

Some of the critical issues that a carefully conceived process design should address are throughput rate, process yield, product purity, space constraints, safety, environmental impact and projected effluents and emissions, production and disposition of byproducts and wastes, and most importantly operating and maintenance costs.

Other factors that generally need to be considered are reliability, redundancy, turndown flexibility and anticipated variability in feedstocks and product specifications.

Some examples of challenging process engineering assignments that have been successfully spearheaded by Dr. Ravi Randhava are noted below:

  • Several computer controlled hydrocracking and hydrotreating pilot plants for the Research Institute of Petroleum Processing (RIPP) in Beijing and Fushun in China.
  • Commercial hydrogen sulfide production plants, a 48 TPD unit in Europe followed by a 120 TPD facility in Southeast Asia.
  • Bitumen upgrading demonstration plant, 142 TPD, for processing bitumen extracted from Canadian oil sands using a novel technology for the in-situ production of hydrogen.
  • A recirculating fluid catalyst demo plant for converting biomass into a bio-oil that can be directly used for heating purposes or converted into an oxygen-free product that is compatible with existing refinery feedstocks. The process uses a circulating bed similar to FCC units in the oil industry.
  • Hydrocracking plant for Archer Daniels Midland (ADM) to make polyols from sorbitol, 2,000 psig, 650°F.
  • High pressure commercial process for making melamine, reactors and bayonet heaters lined with explosive bonded zirconium, 1,500 psig, 900°F.
  • Continuous supercritical CO2 process for decaffeination of green coffee beans, 6,000 psig, 60 foot absorption/desorption columns.
  • Saline water geo-pressured aquifer simulation process, 20,000 psig, 450°F.
  • Process for direct synthesis of dimethyl ether (DME) from natural gas. Demo unit, 10 TPD, with an auto-thermal unit for making synthesis gas, fixed bed boiling water DME reactors and cryogenic separation of reactants.
  • Vapor phase polypropylene process, demo plant for a major US company including a fluidized bed reactor and a comprehensive feedstock purification train. The design was used as a platform to make subsequent units for other
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Conceptual Engineering

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Feasibility Study

The early stages of front end project and process development are critical for the future success of projects involving new technologies and processes. The...

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Detailed Engineering & Design

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Commissioning & Start-Up

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