Introduction to NOx generation in cement industry

The high temperatures and oxidizing atmosphere required for cement manufacturing favor NOx formation. In cement kilns, NOx emissions are formed during fuel combustion by two primary mechanisms:

  1. The oxidation of molecular nitrogen present in combustion air (thermal NOx)
  2. The oxidation of nitrogen compounds in fuel (fuel NOx).
  3. The oxidation of nitrogen compounds in Raw Material (Raw Material NOx)

 

Sometimes, the raw material feed may also contain nitrogen compounds, which may lead to feeding NOx similar to fuel NOx. Because of the high temperatures involved in burning or clinker formation, thermal NOx is the dominant mechanism for NOx formation in kiln systems.

 

Nitrogen oxide (NOx) emissions are among the leading causes of acid rain and smog; their control is a primary objective of environmental regulation. With new legislation increasing the pressure on utilities and heavy industry to reduce NOx Levels, you will find PH1’s VishudhSystem (deNOx/ NOx Reduction system-SNCR)an economic and effective solution.

Why PH1? Why Now?

Proven Technologies We’re engineers, and we’ve been in this business for more than a decade. We know the technologies, and we know how they interact with each other to create a reliable and dependable emissions control system.

 

Emissions Compliance for the long term

Emissions compliance is a legal requirement, not just at your project’s startup, but well into its lifetime. Our experience is based on successful installations ensuring your emissions control system operates long after it has been commissioned.

 

Cost-Competitive

We understand emissions control systems are major project expenses. We can take advantage of common indigenous designs and volume pricing, making PH1’ deNOx system one of the most cost-competitive in the market.

SNCR Based NOx Reduction System

Secondary measures focus on the reduction of NOx which has already been formed and are implemented if emission limits cannot be reached by using only primary measures. Injection of reducing agent (NH3) into the NOx contaminated hot flue gas is the most commonly used method for downstream NOxreduction in the cement industry. This technology is called: Selective non-catalytic reduction (SNCR)

An SNCR system performance depends on temperature, residence time, turbulence, oxygen content, and a number of factors specific to the given gas stream. These factors are taken care during designing of the system

Design and operation factors

Important design and operational factors that affect NOx reduction by an SNCR system are the following:

  • 1) Residence time available in optimum temperature range
  • 2) Degree of mixing between injected reagent and     combustion gases
  • 3) Uncontrolled NOx concentration level
  • 4) Molar ratio of injected reagent to uncontrolled NOx.

DeNOx System Safety Aspects

The SNCR equipment has to be designed according to the local health and safety prescriptions. The legal requirements depend on reagent concentration, storage capacity and the local conditions. Ammonia compounds used for SNCR are caustic substances. Any spillage or leakage could be harmful to people and the environment and has therefore to be avoided.PH1 considers utmost safety in handling Ammonia and helps to reduce the NOx level in a cost effective and efficient manner.

EMISSION STANDARDS – Cement Industry

    In the Environment (Protection) Rules, 1986-

  • (a) in schedule I, after serial number 10 and the entries relating there to, the following serial number and entries shall be inserted, namely :