The technology of increasing the efficiency of boilers while reducing the formation of nitrogen oxides by intensifying the heat exchange of heat with the use of secondary emitters

It is intended for and increase efficiency of combustion of gaseous fuels in boilers and reduction of toxic emissions into the atmosphere.

The disadvantage of many in operation of water heaters and steam boilers is the inefficient heat transfer in the furnace and due to this high temperature of waste gases (up to 200 – 250 ° C) and low efficiency (up to 85 – 87%).

One of the possible and real ways to increase the efficiency of fuel use in boilers, and accordingly increase their efficiency and reduce gas emissions into the atmosphere (including CO2, NOx, etc.), there is an intensification of heat transfer and, respectively, heat output in the boiler room.

In combustion of natural gas in relatively small furnace volumes of boilers with advanced shielding of walls, in terms of the intensification of heat exchange and reliable stabilization of the torch, it is expedient to install intermediate (secondary) emitters – solid heat-heated bodies that are like “thermal mirrors” transmit radiation to the heating surfaces.

The action of intermediate emitters is based on the fact that they perceive heat by selective radiation and convection from combustion products and transmit it to a full spectrum of radiation to water-cooled surfaces located in the furnace. While in stationary mode at constant temperature, intermediate emitters all the incident heat flux on them is re-emitted on the surface of the screen in the form of reflected heat and own radiation.

Installation of intermediate radiators in the boiler room of the boiler provides intensification of radiant heat transfer, which increases heat transfer in the furnace and consequently increases the efficiency of boilers and reduces fuel consumption. In addition, the introduction into the zone of the torch intermediate emitters allows you to reduce the maximum temperatures in the core of the combustion zone, which reduces the formation and, respectively, emissions of toxic substances, primarily nitrogen oxides. As a result of lowering both the maximum temperatures in the combustion zone and the temperatures at the exit from the furnace and behind the boiler, the working conditions are facilitated, reliability increases and the boiler life increases.

Using intermediate emitters allows:

increase the heat output in the furnace of the boiler by 10 – 30%;
to reduce fuel consumption (natural gas) in boilers:
– with productivity up to 1 Gcal – by 3 – 5%,
– by productivity 1 – 6 Gcal – by 1 – 3%,
– by productivity 6 – 30 Gcal – by 0,6 – 1%;
to reduce the formation of nitrogen oxides by 20 – 30%;
to reduce the temperature of exhaust gases at 60 – 90 С;
increase the reliability of operation and increase the life of boilers (by 10-20%, or for 3-5 years) by reducing the maximum temperatures in the combustion zone by 30 – 70 С.
The technology does not require large capital investments and operating costs, the payback period is 1 – 2 years, depending on the type of boiler.

For the manufacture of radiators, refractory materials are used on the basis of oxides or refractory compounds, which provide the possibility of prolonged operation in high temperature in an oxidation-reducing medium, with the possibility of implementing a sufficiently large number of changes in heat.

Technical decisions were made on the use of intermediate radiators in NISSTU boilers of various modifications, as well as in boilers of TBG, DKVR, KV-GM and other productivity up to 30 Gcal / h (up to 50 t / h of steam).