ELECTRIC MODULAR-TRIGGER KILN
WITH AN ENERGY RECUPERATION SYSTEM
FOR FIRING VERMICULTE CONCENTRATES
A. I. Nizhegorodov
Translated from Novye Ogneupory, No. 10, pp. 22 – 27, September 2015.
Original article submitted May 19, 2015.
Possibilities are considered for improving the energy efficiency of electric modular-trigger kilns for firing ver
miculite concentrates. Rationale is given for introduction into the kiln construction of an additional “zero”
module using secondary energy resources. A model of vermiculate thermal assimilation is provided, which
takes account of thermal exergy accumulated within it, absorbed on heating, and transferred in a “zero” mod
ule into energy of grain mechanical transformation. In order to reduce loss of this exergy by vermiculite an
original construction is proposed for a “zero” module, and prediction of the energy efficiency these kilns is
Keywords: electric modular-trigger kiln, firing, heat assimilation, firing module, “zero” module, specific en-
ergy capacity, kiln efficiency, vermiculite concentrate, expanded product.
There are already more than ten years of experience of
firing vermiculite in electric modular-trigger kilns. Each
stage of their development makes a new contribution to im-
proving the efficiency of these units and a reduction in firing
specific energy consumption.
During improvement, as with other complex systems,
there are often new scientific and associated engineering so
lutions making it possible to raise them to the next level. In
 an energy saving system was proposed and considered,
including a recuperator for convective heat and radiant en
ergy (secondary energy resources) and an additional “zero”
heat-insulated, but not electrified, module using secondary
energy resources (SER) for firing vermiculite within this
module in a stage of partly incomplete heat assimilation.
In this article on the basis of analyzing a new model,
based on thermal latent exergy in vermiculite grains not con
sidered previously (it is also considered as a SER), by accu
mulating and increasing its overall volume of heat assimila
tion energy, the possibility is demonstrated of its structural
transfer into deep layers of grains and transformation into de
hydration energy and vermiculite mechanical transformation.
In order to minimize loss of exergy another structural solu-
tion of an additional module is proposed, thermally insulat-
ing vermiculite flow to a maximum.
The aim of these studies was the possibility of improving
the energy efficiency of electric modular-trigger kilns and
substantiation of introducing into the kiln structure a “zero”
module using SER, and also analysis of a model of vermicu
lite heat assimilation taking account of thermal exergy accu
mulated within it, transferred into mechanical transformation
energy of its grains in the “zero” module.
The term “exergy” signifies high quality energy, and its
capacity for completing useful work under conditions of ab
sence of equilibrium with the surroundings, i.e., that part of it
that may be transformed and used. The specific case in ques
tion is singular. Here heat accumulated within vermiculite di
rectly due to conduction is transformed into dehydration en
ergy, phase transition, heating of water vapor and absorbed
gases, and leads to completion of mechanical work in deep
vermiculite layers .
It has been shown in  that about 45% of thermal en
ergy assimilated by vermiculite remains in material ex
panded and heated to 725 – 750°C (q
). So far this part of the
energy has been considered as lost, which corresponded to
the previously adopted (now standard) model according to
which heat assimilation was completed under action of an
Refractories and Industrial Ceramics Vol. 56, No. 5, January, 2016
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