Major Features of DESEIN Engineered Power Plants:

  • Low capital cost without sacrificing operational efficiency or reliability
  • On schedule in design and construction activities
  • High availability
  • Reasonable solution to environmental requirements
  • Coordinated water systems
  • Design and operational benefits from the systems approach to engineering

Single Pass Tower Type Boiler adopted for Thermal Power Plant in India for the first time:

  • For the first time in India, DESEIN had designed and constructed single pass tower type design boilers to produce 690 tonnes per hour of steam at a temperature of 540C and a pressure of 156 ata. The drum type boiler was equipped with horizontal drainable heating surfaces.

  • The entire boiler including the platforms at various levels are suspended from the steel ceiling girders. A passenger lift and freight lift is provided in the pylons for access to various platform levels. Pylons are suspended on well foundations sunk and anchored to hard rock.

  • This design is particularly suitable for Indian Thermal Power Plants because of the high ash content of coal available for burning in Thermal Power Stations and the highly corrosive nature of the ash. This type of design allowed location of coil bends and headers away from the flue gas path preventing directional change of flue gas in the high dense areas of tube locations and lower flue gas velocities - all contributing to much reduced ash erosion on tubes.

The concrete columns adopted for Boiler supporting structures in place of conventional steel columns:

  • This design contributed to cleanliness of the station. It reduced import of high quality steel required for the heavy columns of the Boiler and utilized locally available cement instead. The cost of structures was also reduced by about 10%.

Back-end arrangement of Coal Mills:

  • DESEIN is amongst the first Engineering Consultants which introduced the concept of Coal Mills at the back side of the Boiler and in between Boiler and ESP. This arrangement enabled Turbine House to be free from coal dust and ensured cleanliness of Turbine House, Control Room, Switchgear Gallery, etc.

Adoption of Tube Mills for Boilers:

  • DESEIN has adopted such Mills in Thermal Power Station with the objective of reducing coal mill outage for maintenance and elimination of Mill Rejects Handling System altogether.

Introduction of Direct Ignition Pulverized Coal Burners:

  • The source of substantial expenditure in thermal power stations is found to be the use of oil during boiler light-up. Use of DIPC burners help instant start-up of boiler using pulverized coal and these burners are ignited by spark ignition. Dependence on oil for start-up, stabilization and loading is eliminated resulting in drastic reduction in use of fuel oil. This system has been adopted in Vijayawada Thermal Power Station Units # 3 & 4.

Introduction of Variable Frequency Drive for Induced Draught Fans:

  • This type of system was also introduced in the Vijayawada Thermal Power Station units engineered by DESEIN. This system enables reduction in the auxiliary power consumption because of high efficiency over a wide range of speed, smooth start-up of motors and no limitation in the number of starts, results in the increase of life of motors and integration with the main Instrumentation System.

Vibration isolation system for foundation of dynamically loaded equipments:

  • Spring mounted vibration isolation systems were adopted for the foundation of TG sets, Coal mills, FD, PA and ID fan foundations. The provision of vibration isolation system isolates the equipment vibrations from the sub-structure and foundation and reduces the loading on it to static loading, thus providing for considerable saving in cost and time required for design.

  • The vibration isolation system consists of provision of a number of spring units along with visco-dampers, under the foundation deck slab. The vibrations of the machine and the deck slab are absorbed by the spring units and only static loads are transferred to the supporting sub-structure. With this system, the vertical alignment of the machine can also be adjusted, if required, while in operation, without stopping the machine. A techno-economic study carried out for a 500 MW TG foundation, showed that the cost of the foundation with vibration isolation system worked out less than the conventional foundation, even after allowing for the cost of spring units.

Light-weight maintenance free claddings for Power Plant Buildings:

  • Use of light weight colour precoated galvalume metallic sheets for external cladding for the main power plant building, instead of the brick/block masonry walls, is a new concept in cladding which is being extensively used for the wall and roof cladding of power plant buildings.

  • The metallic cladding comes in two types (viz.) single sheet cladding, and double or sandwich cladding which has outer inner sheets with a layer of insulation in between. The double skin cladding is provided wherever the inside temperature of the building is to be maintained at a constant level especially in areas where extreme ambient temperatures are experienced due to seasonal changes.

  • The metallic cladding gives a neat aesthetic appearance to the building. This cladding is easy, clean and fast to install and does not require any maintenance. The colour coated sheets are ultraviolet stabilized and do not need any repainting during the entire plant life of 20 to 25 years.

Steam Turbines Generators with Auxiliaries:

  • Brushless excitation with rotating diodes is provided eliminating the problem associated with slip rings due to vibration, wear of brushes etc. as is the case with the conventional static excitation.

  • Single pass condensers are installed with cupro-nickel tubes. High pressure and low pressure heaters in the regenerative cycle are provided with horizontal U-tube construction for effective drainage.

  • A highly sophisticated electronic system is provided for Automatic Turbine Run up System (ATRS). This is integrated with turbine stress evaluator to compute stress margins for permitting a safe loading of the turbine.

Digital Distributed Control System:

  • Instrumentation Controls are based on the highly sophisticated Digital Distributed Control (DDC) system with computers etc.

  • DESEIN has built up during the last several years, rich experience in engineering of Digital Distributed Control system for power station applications. It has also engineered a number of Microprocessor based Programmable Logic (PLC) for plant interlocks and sequential controls as well as for control of auxiliary plants such as coal handling plant, ash handling plant, etc.

Other significant design features incorporated in Plant designs:

  • Single pass and double pass condensers;
  • Horizontal and vertical feed water heaters;
  • Spray cum tray cum reboiling type Deaerating heaters;
  • Boiler feed pumps speed control with hydraulic coupling, alternatively with variable frequency drives;
  • Incorporation of Condensate polishing plant in the Boiler feed cycle;
  • Highly sophisticated electronic system for Turbines Run-up System (ATRS) of Turbine, also integrating Turbine stress evaluator.
  • Introduction of numerical protection relays and substation automation systems (SAS) for additional reliability, operational flexibility & reduced maintenance.
  • Introduction of generator circuit breaker concept for increased safety of generator step up transformers, increased life of power plant auxiliary systems and cost reduction.
  • Introduction of high energy efficient electric motors & energy-efficient luminaires.
  • Introduction of indoor Gas Insulated Substations (GIS) in place of conventional outdoor air insulated HV switchyards to economize on space requirements & maintenance costs.