Boilers are an integral part of any process industry. They have applications in power, cement, heavy engineering and textile segments. They are the backbone of the industry and as India's 'Make In India' initiative gains momentum, the spur in domestic manufacturing units and their requirement for power will ensure the growth of the boiler industry as well.

The boiler industry in India is tightly regulated by Indian Boiler Regulations and this is done essentially for one's own safety. This body aptly describes a boiler as "any closed vessel exceeding 22.75 litres (five gallons) in capacity, which is used expressly for generating steam under pressure and includes any mounting or other fitting attached to such vessel, which is wholly or partly under pressure when steam is shut off." Its main function however is to supply energy to the installation's operations. It works by burning fuel in the furnace, the heat from which turns water in to steam that is then used for a variety of purposes. The fuel that is used in the furnace can be anything from wood, coal, oil, briquette, natural gas or even nuclear fusion or fission. There are mainly two types of boilers - fire tube and water tube. Fire tube boilers have hot gases running through tubes inside a sealed container (reservoir) of water. The heat from these gases is used to heat the water ultimately resulting in the creation of steam. Fire tube boilers are a part of history now and are rarely used today. Their main application was in the humble steam locomotive. The more prevalent and commonly used boiler today is the water tube type. These boilers function in a manner opposite to that of the fire tube type and have an increased heating surface. They consist of tubes in which water is circulated, these tubes are surrounded by heat generated from the furnace. While passing through these tubes the water heats up and changes to steam.

Boilers are further split on the basis of their application. Low pressure boilers are limited mostly to heated applications having a maximum operating pressure of not more than 150 psi. High-pressure boilers are used for process loads and operate between a range of 175 to 700 psi. Boilers are also known as steam generators for apparent reasons. Power generation is one sector, which employs boilers on a very large scale. They make use of super critical steam generators, which are capable of instantly converting water in to steam, without letting the water boil. These operate at extremely high pressure of 3200 psi. As these units deal with extremely high pressures they need to be very strongly built. Previous generations used steel plates, which were riveted together. Nowadays, with the advancement of technology steel plates as thick as 35 mm are welded together to form a solid and safe structure.

Boilers comprise of a furnace, which burns fuel and is the source of heat, a reservoir or tank that stores water and supplies it to the tubes, a steam drum that collects steam as it comes up from the tubes. The steam is then utilised to produce energy. This steam however, is saturated steam and contains water. Though this is fine in many applications, it is not ideal for use in power plants. This is because these plants use steam turbines whose blades can get damaged by the water droplets present in the saturated steam. Hence the steam needs to be superheated to rid it of moisture. This work is done by superheaters, which is basically a chamber inside the furnace to which the steam is directed to. This treatment ensures that the steam coming out is completely dry making it suitable to drive the turbine blades. Increase in efficiency is achieved by pre-heating the water in the reservoir. Some of the saturated steam in the steam drum condenses and accumulates in the form of water at the bottom. This water is routed back to the reservoir and here it helps in increasing the temperature of the stored water. Pre-heating is also done by an economiser, a tubular structure that uses the boiler's exhaust gases (flue gas) to heat the water in the reservoir.

There is one more critical element that is essential to the proper functioning of the boiler, and that is the water itself. The water going in to the boiler needs to be pure and neutral (it should neither be acidic nor alkalic), free from suspended solids and dissolved impurities. This not only leads to better efficiency and long-life but also prevents scaling and pitting on the boiler walls, which occur if the water used is hard and not soft water.

The Indian boiler market is showing positive growth for some years now and is expected to grow further. According to the 17th Electric Power Survey Report there are still 33,883 unelectrified villages in the country. The government is planning a huge capacity expansion in this sector with a major chunk of it being accounted for by thermal power. The major players in India are BHEL, L&T, Siemens, ABB, Crompton Greaves and Doosan Heavy Industries. BHEL is clearly the behemoth in the thermal power segment with over 65 per cent of the market share. The boiler market has been growing at a CAGR of 24.53 per cent and is anticipated to reach a three-fold increase amounting to US Dollars 11.7 billion by 2022. Foreign Direct Investment (FDI) inflows have also been steadily increasing, reaching USD 3 billion during the year 2012-13.

The share of Super-Critical technology in the 11th Five-Year Plan was just 14 per cent. This share has risen to almost 60 per cent in the current 12th Five-Year Plan (2012-17). For the 13th Plan, all new coal plants should have Super-Critical (SC) technology. This has been done with a view to promote cleaner tech. Therein lies the problem, Indian manufacturers don't have manufacturing experience in SC technology. Most of the orders for SC sets have been bagged by foreign firms (nearly 45 per cent) out of which Chinese companies have captured 80 per cent. Other benefits that Chinese firms come with include cost-competitiveness and faster delivery time. Furthermore, concerns over domestic coal shortage and dependence on costlier imported coal will have an impact on the government's ambitious expansion plans. Better design of the boilers is also felt to confront load fluctuations and blending coals with different calorific value.

Under the 'Make In India' campaign, the Department of Industrial Policy and Promotion (DIPP) has pledged full support in enabling policy and creating a regulatory environment. They have already undertaken initiatives such as self-certification and third party inspection, both of which are needed to improve quality and maintain the all-important safety aspect in this critical industry.

The Indian boiler industry is all set to explode on the growth trajectory. What is needed is operational expertise, enhanced competitiveness, prompt deliveries and availability of cheap raw materials. If all these factors are met, then there will be no stopping the Indian juggernaut.