Energy-saving, ecology and development of boiler building in Ukraine
Lack of boiler building plants, which manufacture boiler equipment for commercial power industry, deficit of energy-producing fuel and difficult environmental situation determined the features of commercial power industry of Ukraine.
Based on the accumulated work experience gained in various industry fields, i.e.: in metallurgy, at coking plants, oil and gas processing plants, enterprises of Ukrtransgaz, in sugar industry, at oil extracting plants, machine-building enterprises and food enterprises, Kharkov boiler building company “Kotloenergoproject” developed a concept of comprehensive solution of environmental and energy-saving issues during construction or reconstructions of energy facilities at Ukrainian industrial enterprises considering individual features of available fuel, the structure of secondary energy resources and environmental situation.
Within this concept our enterprise has developed and deployed several technological solutions, which allow to save on fuel and reduce ecological impact.
The main fields of Kotloenergoproject’s operation are:
- Development, manufacturing, assembly and commissioning of new steam and water-heating boilers with high efficiency factor (more than 94%). These boilers make it possible to use both conventional fuel kinds and secondary energy resources of enterprises.
- Reconstruction of existing boilers and boiler houses in order to:
- increase or decrease steam generation;
- increase of efficiency factor;
- reduction of water-use and effluent;
- ensure reliable operation of boilers on boiler feed water with high salts content;
- reduction of harmful emissions into atmosphere.
- Installation of steam and gas turbines in order to provide enterprises with their own thermal and electric energy.
- Design and building of heat-recovery boilers.
Today, neither Ukraine, nor Russia manufacture boilers that can work on flammable gases from metallurgic, coking and oil-processing plants (such as coke and blast-furnace gases, fuel gas from oil- and gas-processing plants), as well as on so called “non-traditional” types of fuel, such as sunflower and buckwheat hulls. At the same time, these types of fuel are burnt in boilers designed to work on natural gas and mineral oil and more or less suitable to burn the above mentioned fuel types. Thus, individual design of boiler units suitable for specific consumers of thermal energy and using all the secondary energy resources of this enterprise.
Another successful technical solution, which allows to obtain energy saving and environmental effect, is represented by self-adjusting flexible-fuel flat flame burners. These make it possible to burn the variety of fuel types (from coke, blast-furnace gases to pulverized coal and mineral oil) both simultaneously and individually.
In order to maintain the nominal steam temperature in a wide range of fuel ratios, the burners of low-grade fuel are usually located in the bottom part of the furnace, whereas the burners of high-grade fuel are located in the upper tiers. However, this results in increased number of burners, makes the boiler design more complicated and makes it difficult to support the optimum fuel and air regime during the furnace operation.
Use of vortex flexible fuel burners reduces the number of burners and makes boiler maintenance simpler. On the other hand, this narrows the adjustment range of heat share of low-grade fuel based on requirements to maintain the required temperature of superheated steam.
The problems of burning low-grade gases with high-grade fuel can be successfully solved by using self-adjusted single-fuel flat-flame burners (SSFFB), developed and improved by “Kotloenergoproject” specialists based on calculated and experimental analysis. Improved flat-flame burners are widely used at iron industry enterprises of Ukraine.
Reconstruction of flexible fuel boilers to work with flat-flame burners ensures:
- reduction of burners’ number from 6-10 to 2 pcs on the boilers with steam production capacity 75-230 t/hour (steam pressure – 39-100 kp/cm2; temperature of superheated steam – 440-540°С), which makes the layout of gas and air ducts as well as boiler utilization simpler; increases reliability of work and provides 1.5-2 times longer fail-free period of boiler operation;
- reduction of sulfuric acid corrosion and plugging of low-temperature surfaces with sediments (economizer, air pre-heater) during burning of sulfur-containing fuel, such as coke gas and mineral oil;
- stabilization of temperature of pre-heated steam in a wide range of values of blast-furnace gas share during its burning together with coke and natural gas and mineral oil;
- increase of blast-furnace gas share maintaining the nominal load of a boiler;
- 30-40% reduction of nitrogen oxide emissions;
- increase of reliability of furnace screens due to high injection capacity of a common burner flare and leveling of local heating load;
- simplification of boiler automation layout and increase of efficiency of fuel-air ratio adjuster, when working with several fuel types;
- 2% increase of efficiency factor due to burning optimization.
It should be noted that commercially manufactured products of Russian and foreign boiler building plants are not suitable for either untraditional fuel types or water resources of Ukraine. None of the commercially built boilers with steam superheater can work with feeder water with salts content more than 450 mg/kg under the normal value of continuous blow-down. There is no such water in many parts of Ukraine. For example: Poltava — 600-1,000 mg/kg, Donbas — 800-1,200 mg/kg etc.
Our enterprise developed a series of drumless steam boilers, which work on feed water with high salts content – up to 2,500 mg/kg. Drumless boilers with natural water circulation are designed for feed water with high (up to 2,500 mg/kg) salts content at normal value of continuous blow-down (10%). Separation of water-steam mixture is done in cyclone separators, coupled to circulation circuits.
The main advantages of drumless boilers include:
- operation of boilers on boiler feed water with high salts content;
- quick launch (reaching operating parameters within 10 minutes) as there are no thick wall elements (drum);
- unlimited resource before write-off;
- possibility to manufacture all the boiler elements by special repair companies;
- minimum thermal response.
For enterprises consuming both high-grade and low-grade steam (e.g. Oil extraction plants) with high salts content in boiler feed water, a design to obtain secondary steam from the blow-down water in a steam transformer can be recommended. This design was developed by “Kotloenergoproject” for one of oil extracting plants.
The boilers installed in the factory’s boiler house generate steam at 24 kp/cm2 pressure and 320-350°С temperature. Partially, steam of the above mentioned parameters will be used for oil refining, whereas another part will be streamed through PRDS for oil extraction (P = 12 kp/cm2 and t=200°С). The continuous boiler blow-down accounts for 50-60% due to high salts content in the boiler feed water (1,000 mg/kg).
Using steam converter instead of PRDS appeared to be an optimum solution for this thermal design as the earlier generates the secondary steam from the blow-down water at the expense of heat of high-grade steam condensation. Condensed water vapor of heating steam returns back for boiler feed water softening. Thus, it is possible to reduce blow-down water use by 2% of the total steam generation of boilers.
At the same time fuel consumption is reduced due to reduction of heat loss from blow-down water; water consumption of the boiler house is also reduced along with the amount of chemicals for water cleaning and the volume of drainage.
In the field of small-scale power generation our enterprise has developed and manufactures steam and water-heating boilers, which can substitute off-market and physically worn-out boiler units in existing (e.g. NIISTU boilers) and in new boiler houses.
The specifications of boilers satisfy the actual regulatory requirements (efficiency factor – more than 93%). They have been developed keeping the peculiar features of their use in Ukraine (fluctuations of gas pressure; bad quality water) in mind.
The work experience of our enterprise proves that Ukraine has got all the necessary technological capabilities to build medium power boilers for industrial enterprises and heat-generating boiler houses.