International Journal of Modern Trends in Engineering and Research

www.ijmter.com e-ISSN No.:2349-9745, Date: 28-30 April, 2016

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Furnace Nozzle Cleaning Standardization Magdum Manoj1, Shukla Tushar2, Khated Aniket3

1Mechanical Engineering, SNJB’s K.B.Jain College of Engineering 2Mechanical Engineering, SNJB’s K.B.Jain College of Engineering 3Mechanical Engineering, SNJB’s K.B.Jain College of Engineering

Abstract - Although the great majority of carburizing is still carried out at atmospheric pressure, recent developments in vacuum furnaces and steel technology have meant that carburizing can now be carried out in a more environmentally friendly way under low pressure. In this process huge furnace is used for carburizing with number of nozzles. This are made up of Inconel alloy. Inconel is a alloy derived from effect of Nickel-Chromium matrix. This nozzles are used to pass acetylene and hydrogen gas to the main inlet of furnace. Due to certain chemical reaction this nozzles are choked up by tar, sludge, soot or carbon particles. Nozzles are of very minor diameter approximately 2mm. Certain traditional methods are used such as to replace the entire set of nozzle to swipe out the problem of choking. This report describes the current state of the art and practical experiences with low-pressure carburising nozzles. Keywords - Inconel, nozzle, carburizing, soot, sludge

I. INTRODUCTION Of the many technologies available today to improve the performance of engineered surfaces, carburising is one of the most common. Carburising is enduringly popular because it uses a higher temperature than most thermochemical processes so that a deep hard layer can be formed in a short time. The great majority of carburising takes place at atmospheric pressure in an atmosphere containing large quantities of carbon monoxide. The benefits achieved by vacuum carburizing can be realized in high volume, critical component manufacturing. Vacuum carburizing has proven itself a robust heat treatment process and a viable alternative to atmosphere carburizing. Low pressure carburizing furnace is used in BOSCH Pvt. Ltd. for hardening of various components. These are also known as vacuum furnaces. Nozzles are used in the low pressure carburizing furnace through which gases pass. It passes the gas namely Acetylene, Hydrogen and Nitrogen. The process is carried out at very high temperatures. These temperature is responsible for various process carried out in furnace. While this process is carried on, various chemical reactions takes place. During the process due to chemical reaction between the gases sludge is formed in the nozzles. We are focused on the above problem. Our first preferences towards the problem solving is to drill the holes in nozzles by using specific parameters.

II. CARBURIZING In low-pressure carburising (LPC), the vacuum furnace is evacuated after charging. When the pressure has dropped below 10Pa, the furnace chamber is effectively free of oxygen and the heating cycle can start. The charge is heated to between 790 and 1040°C in up to three stages, depending on

International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 3, Issue 4, [April 2016] Special Issue of ICRTET’2016

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the carburising temperature and the sensitivity of the components. Once the whole charge has reached the carburizing temperature, the first carburising phase is initiated by admitting the hydrocarbon into the furnace at pressures between 10 and 1000Pa. Carbon transfer is so effective that the austenite is saturated with carbon after only a few minutes. The first carburizing phase must therefore be stopped after a relatively short time by interrupting the gas supply and evacuating the furnace. Carburization is a heat treatment process in which iron or steel absorbs carbon liberated when the metal is heated in the presence of a carbon bearing material, such as charcoal or carbon monoxide, with the intent of making the metal harder. Depending on the amount of time and temperature, the affected area can vary in carbon content. Longer carburizing times and higher temperatures typically increase the depth of carbon diffusion. When the iron or steel is cooled rapidly by quenching, the higher carbon content on the outer surface becomes hard via the transformation from austenite to martensite, while the core remains soft and tough as a ferritic and/or pearlite microstructure.

III. PROBLEM DEFINITION The process is carried out at very temperatures and due to certain reactions between gases carbon deposition takes place on the components. Also these reaction is so effective that the nozzles present inside the furnace gets choked up. The nozzle get choked by soot, sludge which are nothing but the carbon particles. Due to this the flow of gases through the nozzle is stopped. Hence the problem is so critical that it cannot be easily solved.

IV. PROBLEM SOLUTION

The solution which was usually used was of replacing the whole nozzle setup. This method results in high cost and company needed to stop it and find alternate solution. The soot formed is so hard that it cannot be cleaned easily. So we found a solution and started drilling. Usually drilling is used for making holes and the same principle we used here. We used a 2mm drill made of carbide to drill the nozzle. Currently the method is worth working and the material viz. soot and sludge are removed. These method makes easy to flow the gases which was initially going in process.

Figure 4.1 Set of nozzles on the furnace door

International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 3, Issue 4, [April 2016] Special Issue of ICRTET’2016

@IJMTER-2016, All rights Reserved 889

Figure 4.2 Cleaned nozzle & blocked nozzle

CONCLUSION

A great deal of experience has now been gained operating LPC systems around the world with various process parameters, different modes of operation and types of vacuum pumping equipment. The problems that arise are familiar and can be resolved by selecting the right approach for the given process type. However, for typical LPC furnaces using propane and generating a lot of soot and tar, operating reliability can be assured by using Drilling Process, Or by changing of nozzles set up. Many LPC carburized components can be designed so that they can be quenched with high pressure nitrogen.

REFERENCES

[1] Low pressure carburizing services for the transmission industry’, Heat Treater Guide, 2012. Löser K. D., Heuer V. D., Molz J. and Hiller G. [2] Herring D., Practical and Scientific Aspects of Low Pressure Carburizing, 2001 Heat Treating Conference Proceedings, ASM International.