Revamping Options

Other measures, involving more additional hardware and engineering work, are introduction of combustion air preheating and reducing the primary reformer load. 

The fact that more than 40% of world ammonia plants are older than 20 years suggests that there is a major potential for revamp projects, even in plants which have already made modifications. 

---

Filippi, E. and Pinauda, L., Casale Offers More Ammonia Revamp Options , Fertilizer International, pp. 27, July 2001. 

Table 3 compares the results of the various revamp options. 

The following VIPs and techniques are useful to develop holistic revamp options. These VIPs are also proven to significantly improve profitabihty of the projects (Green and Perry, 2008). 

Purpose To set the project objectives, basis, assumptions and preliminary economics To generate alternative revamp options and establish the best revamp option To fully develop the revamp option To complete engineering, procurement and construction To measure success of the revamp project and document key highlights and lessons learned... 

Preliminary project Revamp options and Vendor quotations for commissioning punch... 

Apart from utilizing the excess of capacity in the plant equipment, the following revamp options that do not involve capital expenditure are very useful. For quick benefits, some of these options can be implemented before implementing the complete revamp project. 

Potential revamp options requiring capital cost are listed in Tables 2.6 to 2.16 for different... 

Table 2.6 Revamp options for hydraulic systems, separators and control valves. Equipment/...

Table 2.8 Revamp options for reciprocating compressors, centrifugal fans, blowers, centrifugal pumps and electric motors.

Table 2.9 Revamp options for heat exchangers and fin fan (or air) coolers. Equipment - Objective Options...

Revamp options for reactors, mixers, distillation columns and vacuum... 

Table 2.13 Revamp options for plant air system, power generation, fuel system, waste heat recovery and waste water treatment.

Table 2.14 Revamp options for cooling towers and cooling systems.

Table 2.15 Revamp options for deaerators, boilers, steam turbines and steam system. Equipment/system - Objective Options...

Table 2,16 Revamp options for debottienecking and revamping storage faciiities.

In the FEED stage, conduct process hazard analysis, RAM, predictive maintenance, value engineering and constructability studies for accurate scoping of the most profitable revamp option... 

For the given utility costs. Cases 1C and IG are the attractive revamp options for the scenarios with low and high capital cost spending, respectively. If the cost of MP steam (used in SJE) is lower at 75% compared with the base case (due to credit from power generation at steam turbines), then the attractiveness of Cases D, E, F and G reduces. For this scenario. Cases IB and 1C are attractive if lower capital options are preferred. 

An adiabatic pre-reformer is an attractive revamp option, especially when the aim is to minimize steam export and/or to increase plant capacity in cases where the primary reformer is the bottleneck. 

Several revamp options are available for modification of the carbon dioxide removal section depending on the type of carbon dioxide removal process. The processes mostly used in ammonia plants are chemical absorption processes based on either hot potassium carbonate (HPC) such as Benfield, or Vetrocoke, or amine solutions such as MEA. The chemical carbon dioxide removal processes may be improved or replaced with a physical process in which the absorbent is regenerated by simply flashing off carbon dioxide. In this way the need for regeneration heat may be reduced or eliminated. A physical carbon dioxide removal system may result in energy savings of 0.01-0.35 Gcal/MT ammonia. 

The main revamp options of the ammonia synthesis loop are the installation of molecular sieves for drying of the make-up gas, installation of a purge gas hydrogen recovery system, and improvements in the ammonia synthesis converter system. 

---