Control Of Nitrogen Oxide Emission

It is proposed to design a process plant that will control nitrogen oxide emission from a plant that is producing 90wt% nitric acid of 30,000 tonnes of nitric acid. This capacity is based on 8000hours of operation per year i.e. 330 days. It is proposed that this plant will be located in any location where there is substantial release of nitrogen oxides.

The process plant will control about 90% of the nitrogen oxides being emitted from the nitric acid plant.

The controller which is called a control reactor for this design project work controls two different processes. One of the processes has a tail gas temperature from the absorber within the temperature range of 425oc and 520oc. While the other process works with a tail gas temperature from the absorber within the temperature range of 340oc and 520oc. Both processes 1 and 2 use Iron zeolite as their catalyst but process 1 uses ammonia in combination with the Iron zeolite catalyst and process 2 uses an hydrocarbon (ethane) in combination with the Iron zeolite catalyst.

After the entire design was done, the costing of the entire project was done and from the analysis of the costing, it was found that the purchase cost of all the process equipment was N 139,625,80.

While the annual operating cost of the entire process was N 181250.

Introduction

1.1    Aim and Objectives

1.1.1 Aim

1.1.2 Objectives

1.2    Scope of Study

1.3    Relevance of Study

CHAPTER TWO

Literature Review

2.1   Definition of Nitrogen Oxides

2.1.1 Nitric Oxide and Nitrogen Dioxide

2.1.2 Dinitrogen Tetroxide

2.1.3 Nitrous Oxide

2.1.1 Nitrous Acid and Nitric Acid

2.1.4. Nitric Acid

2.2    Nitrogen Oxide Emissions

2.3    Harmful Effects of NOx Emissions

2.4    Nitrogen Oxide Emission Mechanisms

2.5    Removal of NOx from Combustion Gases

2.5.1 Iron-Magnesium Combustion Catalysts

2.6    Reduction of NOx with Fuel Borne Combustion Catalyst

2.7    Mechanism of NOx reduction with a Combustion Catalyst

2.8    Description of Nitrogen Oxides

2.9    Where does NOx come From?

2.10 How does NOx affect the Environment

2.11 Are there other NOx Related Issues?

2.12 What Abatement and Control Principle apply?

2.13 What abatement technologies are available

CHAPTER THREE

3.0   Plant Layout

3.1   Process Selection

3.2   Process Description for Process One

3.3   Process Description for Process Two

3.4    Process Flow Diagrams (PFD)

3.4.1 Process Flow Diagram for Process One

3.4.2 Process Flow Diagram for Process Two

3.5   Process Flow Diagram for Nitric Acid Production

CHAPTER FOUR

Material and Energy Balance

4.1    Material Balance

4.2    Energy Balance

CHAPTER FIVE

Equipment Design and Specification

5.1    Manual Design of the Absorption Column

5.2   Manual Design of the Nitrogen Oxide Control Reactor

5.3    Manual Design of the Compressor

5.4   Computer Aided Design of the Absorber Using Hysys

5.5   Computer Aided Design of the Compressor Using Hysys

CHAPTER SIX

Cost Estimation of the Project

CHAPTER SEVEN

Safety and Loss Prevention of the Process Plant

CHAPTER EIGHT

Conclusion and Recommendation

8.1   Conclusion

8.2  Recommendation

REFERENCES 

2.1 Toxic agents

2.2 Nitrogen oxides (NOx)

4.1 Summary of the material balances for the absorber

4.2 Summary of the material balances for the acid (HNO3)

4.3 Summary of all the components to the scale up production rate

4.4 Summary of all the material balances for the control reactor

Fig.1: NOx map

Fig.2: Ozone map

Fig.3: Process flow diagram for process one

Fig.4: Process flow diagram for process two

Fig.5: Process flow diagram for nitric acid production

Fig.6: Computer aided design for the absorber using HYSYS

Fig.7: Computer aided design for the compressor using HYSYS

This design project work is intended for the control of nitrogen oxide emissions. Nitrogen oxides can emanate from different sources which are generally classified into stationary and mobile source. But this design project work was carried out for stationary source only and the source of the nitrogen oxide is from a nitric acid plant.  Chapter one gives a general information of this design project work. It clearly states the major aim and objectives of this design project work, the relevance and scope of this design project work. Chapter two gives a general knowledge of nitrogen oxide emission.  Chapter three of this design project work shows a simplified process flow diagram for the processes adopted for the control of the nitrogen oxide emission with its description. It also shows the process flow diagram for the production of nitric acid. From the process flow diagram, a lay man will be able to have an idea of the material flows.

In chapter four a detailed material and energy balance calculations were performed. This was done in order to account for all the components used for this design project work. Without a proper material and energy balance, it will be very difficult to carryout the design of the major process equipment, thus, the material and energy balances were done in order to generate suitable data that can be used for the design of the major process equipment. Chapter five gives a detailed design of the major process equipment. The major process equipment that was designed are an absorber, a control reactor and a compressor. Both manual and computer aided design using HYSYS were carried out. After all these were done, a proper costing of the entire project was done.