WAYS FOR INCREASING EFFICIENCY OF A HEAT RECOVERY UNIT
S. Ya. Davydov,
I. D. Kashcheev,
and N. V. Silina
Translated from Novye Ogneupory, No. 8, pp. 23 – 25, August, 2007.
Original article submitted January 27, 2007.
The authors present analysis of variants of using low-potential heat, which improve the efficiency of steam
gas-fired boilers, air heating, and cleaning waste gases from toxic emissions in thermal machines. In order to
achieve a more complete moisture removal from combustion products, an upgraded design of a contact heat
recovery unit is proposed equipped with a drip pan with cooled packing.
Technical progress should involve significant improve
ment of the use of natural resources and a lower impact on
the environment. The energy-saving potential in Russia con
stitutes 35% of the current energy consumption, which is
equivalent to 350 – 400 million tons of conventional fuel.
The use of a major part of this potential would be 5 – 10 times
cheaper than the cost of extraction and production of energy.
The contemporary environmental approaches are based on
the need of a wide implementation of the most effective pro-
cesses in power-related industry, which will improve its effi-
It is possible to achieve substantial saving of fuel and en-
ergy by wide recycling of low-potential fuel waste resources
generated at industrial enterprises. The cost of recovery of
waste heat is 2 – 3 times lower than the cost of extracting and
transporting fuel-energy resources. One of possible heat
sources is using heat-recovering plants based on combustible
or thermal recyclable resources . According to the current
standard designs, the waste gas temperature in indus
trial-and-heating boilers is 130 – 150°C, the dew point is not
higher than 60 – 65°C even in the case of a significant air ex
cess. This prevents a fuller use of the maximum heat of gas
combustion. Therefore, increasing the fuel use coefficient in
the industry and the power sector is one of the main ways in
An efficient contact heat-recovery unit (CHRU)has been
developed commissioned by the Ministry of Industry, Ener
gy, and Science of the Sverdlovsk Region . The evolution
of the CHRU was investigated; the known variants of reco
vering low-potential heat from energy and industrial boilers
and technological and power machinery, as well as blow air
heating and a combined variant of using contact economizers
and air heaters were analyzed.
The state and degree of investigation of units for recover
ing residual moisture from waste gases of CHRU was esti
– filters, mist eliminators;
– low-speed fibrous mist eliminators;
– high-speed mist eliminators;
– mesh splash eliminators.
The analysis established that an integrated heat recovery
system can raise the boiler efficiency by about 10%. The
testing results have corroborated the efficiency of the in-
tegrated heat-recovery system and its good prospects for
boilers and heat and electric power plants using natural gas
as fuel. In designing a new type of a CHRU, preference
should be given to the variant of water heating due to reco
vering low-potential heat of the products of natural gas com
bustion and installation of a special design of drip pans along
the gas flow.
A new variant of a CHRU with improved thermal effi
ciency parameters has been designed. It is demonstrated that
the use of concealed heat of evaporation of the combustion
products is a promising line for improving the thermo
dynamic efficiency of such devices. Direct contact heat ex
changers, unlike recuperative and regenerative heat exchan
gers, need less metal. The mass- and heat-exchange coeffi
cients in their working volume are higher, therefore, they are
more efficient. Thermal and design analysis of the new plant
has been carried out. It is established that the proposed design
can be most efficiently used in the power sector and industry
where substantial emissions of low-potential heat take place.
Drip pans are provided for a more complete removal of
moisture from the combustion products.
A drip pan with cooled packing is installed in the body of
the considered contact heat recovery unit. The packing is
chilled by a cooling pipe that has welded fins passing radi
cally across the packing layer nearly to the wall of the recov
Refractories and Industrial Ceramics Vol. 48, No. 3, 2007
1083-4877/07/4803-0183 © 2007 Springer Science+Business Media, Inc.
Ural State Technological Institute (Technical University), Russia.