AMMONIA PLANT PRIMARY REFORMER OPTIMIZATION

Primary Reformer is the heart of the ammonia plant, where by steam-hydrocarbons reforming reaction hydrogen is produced. Reforming reactions being endothermic in nature consume a large amount of energy. Approximately 80% of ammonia plant fuel consumption is at primary reformer burners. In this backdrop energy optimization at primary reformer is of cardinal importance.

To optimize the performance of primary reformer, following factors play an important role:

1. FURNACE DRAFT:

Slightly negative pressure in a furnace is known as draft. Hot flue gases flow out of the furnace and combustion air draw into the furnace due to draft.

- High Draft cause more combustion air to enter into reformer, this consumes Significant heat of combustion which could be used otherwise for reforming. Moreover, higher drafts damages insulation installed onto inside walls of reformer.

- Conversely, lower draft may lead to positive pressure inside the furnace and heat accumulation inside reformer damage radiant and convection section metallurgy.

Therefore, always maintain reformer draft in an optimum range for efficient and safe operation.

2. OXYGEN CONTENT IN FLUE GASES:

Excess oxygen level is maintained in the flue gases to ensure complete combustion of fuel. However, excess oxygen levels must be in an acceptable range for optimum operation.

- Lower excess oxygen may cause incomplete fuel combustion

- Higher excess air causes decreased heat available for reforming / convection section.

Proper mixing of air fuel mixture in burner should be adjusted for optimum excess oxygen level in furnace vis-a-vis furnace efficiency. For excess oxygen monitoring online oxygen are also installed at flue gases stack.

3. REFORMER OUTLET TEMPERATURE:

Reformed gases outlet temperature is the best indicator whether reforming reaction is near completion or not.

- Lower reformed gases outlet temperature indicates reaction conversion is away from equilibrium. This lower conversion ends up as increased inert content in synthesis loop and decreased ammonia plant production.

- Conversely higher outlet temperature may cause significant energy loss and increase plant energy index.