Gas generator

The proposed gas generator includes an isothermal vessel for a cryogenic liquid, the vessel being connected via an electrically controlled valve to a supercharging evaporator, a nozzle unit arranged in the upper part of the gasifier and connected by an electrically controlled valve to the lower part of the cryogenic liquid vessel, the gasifier being partially filled with a heat-accumulating substance and provided with a deflector situated above the nozzle unit and an electrically controlled sealing unit; in the lower part along the gasifier axis are provided a separator and a toroidal elastic casing attached to the bottom of the gasifier, the cavity of the casing communicating via the main pipe (provided with a pre-heating heat exchanger) with the upper part of the iso-thermal vessel, while the heat-accumulating substance is situated above the surface of the toroidal elastic casing, the electrically controlled sealing unit being situated at the separator outlet. The nozzle unit includes jet nozzles arranged in the lower side of the nozzle unit; water or solutions in water are used as the heat-accumulating substance.

FIELD OF THE INVENTION 
The invention relates to gasification technology and can be used basically 
in the field of fire fighting for generating a large quantity of a fire 
extinguishing substance. This apparatus is necessary for extinguishing 
fires of large dimensions, such as fires in industrial plants, in closed 
or semi-closed buildings, for extinguishing burning liquids and gases, 
e.g. in oil and gas wells. 
In a more narrow field of use the gas generator can be effectively applied 
in high performance laser technology, for instance for gas dynamic CO or 
CO.sub.2 lasers which require the production of a great quantity of gas in 
a short time and at a low temperature. 
The invention also relates to a field where an intensive supply of a 
gaseous product of high productivity is required. An example of such an 
area of usage is the production of nitrogen or other indifferent gases in 
containers of large storage capacity for preserving perishable foodstuffs, 
such as meat, eggs etc., and also for the preparation of tankers for 
transporting dry goods, which are used to carry corn or other foodstuffs. 
DESCRIPTION OF THE BACKGROUND ART 
At the present time various types of gas generators have been developed and 
are used in industry, which use external (electrical) energy as well as 
energy from th e environment, i.e. so-called surface gasifiers. One 
example of such a gasifier is the low-pressure gasifier GH-0,035/1,6 (SU 7 
186 692) consisting of two cylindrical high-pressure tanks for storing 
cryogenic liquids under a pressure of up to 1,6 MPa and transporting them, 
and a production vaporizer for gasification. The production vaporizer 
consists of a block of panels arranged in a frame. The liquid product is 
discharged from the tank under pressure, is fed into the panels of the 
vaporizer and gasifies by heat exchange with the environment without 
additional use of energy. There is a whole range of low pressure cryogenic 
gas generators in use that work in analogy to this principle. However, 
they all have essential disadvantages, that is, their low productivity of 
the gaseous product in conditions of mass production. Thus, the maximum 
productivity of a GHK 25/1,6-2000 apparatus is 2200 cubic meters per hour 
(0,6 cubic meters per second) at an occupied space of 86,6 square meters 
and a mass of 19,2 tons. 
More effective is a gas generator for use in fire extinguishing plants 
according to SU 1 678 391, which comprises an isothermal vessel, an 
electrically controlled valve, and a supercharging evaporator. The 
isothermal vessel in this gas generator is connected via an electrically 
controlled valve to the lower part of the evaporator of the gasifier and 
to a mixing chamber, in which turbulence-creating grids and filling inlets 
are arranged. However, the essential disadvantages of this gas generator 
are the following: Firstly, in this gas generator construction the 
quantity of gas generated cryogenic liquid is determined by the mass of 
the heat-accumulating inlet. Therefore an increase in the productivity of 
the apparatus is dependent on an increase in the mass of the 
heat-accumulating inlet, which, as a rule, is made of a metal with a great 
heat capacity or of natural materials, such as gravel, crushed stone etc. 
Secondly, additional time and the supply of external energy are needed to 
prepare the apparatus for the second working cycle, i.e. to reheat it. 
SUMMARY OF THE INVENTION 
The proposed gas generator comprises an isothermal vessel for a cryogenic 
liquid, said vessel being connected via an electrically controlled valve 
to a supercharging evaporator, a nozzle unit, a pre-heating heat 
exchanger, and a main supply pipe, in which the nozzle unit is arranged in 
the upper part of the gasifier and is connected via an electrically 
controlled valve to the lower part of the cryogenic liquid vessel, the 
gasifier being partially filled with a heat-accumulating substance and 
provided with a deflector situated above the nozzle unit and an 
electrically controlled sealing unit; in the lower part along the gasifier 
axis are provided a separator and a torodial elastic casing fixed to the 
bottom of the gasifier, the cavity of the casing communicating via the 
main pipe (provided with a pre-heating heat exchanger) with the upper part 
of the isothermal vessel, while the heat-accumulating substance is 
situated above the surface of the toroidal elastic casing, the 
electrically controlled sealing unit being situated at the separator 
outlet. 
In the proposed gas generator the nozzle unit comprises jet nozzles 
arranged in the lower side of the nozzle unit. Moreover, water or 
solutions in water are used as the heat-accumulating substance. 
The arrangement of the nozzle unit with the jet nozzles directed towards 
the gas stream enables an intensification of the heat exchange process. 
The proposed gas generator, in which water or solutions in water are used 
as the heat-accumulating substance, does not have the disadvantages of the 
prior art. For the evaporation of the cryogenic liquid the energy stored 
in the heat-accumulating substance is used not only by way of its heat 
capacity, but also the energy of its crystallisation is used (the energy 
generated by the freezing of water). The amount of water needed for the 
evaporation, e.g. for the first kilogram of nitrogen is approximately 200 
g altogether. This factor allows to greatly reduce the mass dimensions and 
the costs of the apparatus; and the energy consumption for fixing the 
inlet is reduced virtually to zero, since the ice that is formed is 
discharged from the apparatus to the outside with the rest of the water. 
Also, the productivity of the apparatus is determined only by the pace of 
the feeding of cryogenic liquid into the evaporator and by the pressure 
loss of the main outlet pipe for the gaseous product.

DETAILED DESCRIPTION OF THE INVENTION 
The apparatus (see FIG.) comprises an isothermal vessel for a cryogenic 
liquid (compressed nitrogen, for instance) 1, electrically controlled 
valves 2, 4, 5, 6, 7, a supercharging evaporator 3, a pre-heating heat 
exchanger 8, main supply pipes 15 and 16, by which the isothermal vessel 1 
is connected to the gasifier 9. In the lower part of the gasifier a 
torodial elastic casing 12 and a separator 11 are situated; the space 
between the walls of the separator 11, the gasifier 9 and the elastic 
casing 12 being filled with water. The lower part of the gasifier is 
limited by an electrically controlled sealing unit 14. In the upper part 
of the gasifier 9 a nozzle unit 10 with jet nozzles, a deflector 13 and an 
outlet pipeline 17 for the gaseous product are arranged. 
EMBODIMENT OF THE INVENTION 
The proposed gas generator works in the following way. At the command to 
begin the technical process of the gasification of a cryogenic liquid the 
electrically controlled valve 2 starts to work, the liquid is supplied 
into the supercharging evaporator 3 and in gaseous form is fed into the 
upper part of the isothermal vessel 1. Thus the necessary pressure is 
built up in the isothermal vessel 1. When a predetermined pressure is 
reached in the isothermal vessel 1, the electrically controlled valves 5 
and 7 open. 
The liquid is supplied via the main supply pipe 16 into the nozzle unit 10 
and is sprayed by the jet nozzles towards the water. When the cryogenic 
liquid comes into contact with the water, a violent evaporation process of 
the cryogenic liquid ensues; simultaneously, the water partially 
crystallizes. In order to prevent the formation of an ice skin on the 
water surface, a gaseous phase is supplied from the gas cushion in the 
upper part of the isothermal vessel through the main supply pipe 15 into 
the toroidal elastic casing 12, which, as it fills up, lifts the lower 
layers of water to its surface and expels the ice particles into the 
separator 11, thus clearing the water surface. The evaporated cryogenic 
liquid rises to the upper part of the gasifier 9 and flows through the 
duct 17 into the vessels of a fire extinguishing apparatus. To ensure that 
no ice particles are expelled together with the gas, a deflector 13 is 
arranged in the upper part of the gasifier. The flow that impinges the 
deflector is stopped and, changing direction, circumvents the deflector 
and is discharged into the duct 17, while the ice particles fall down into 
the separator 11. When the evaporation process is completed, the 
isothermal vessel 1 is discharged of the gaseous remains of the product 
through a discharge pipe. The electrically controlled sealing unit 14, 
situated in the lower part of the gasifier 9 opens; ice and remains of 
water are discharged from the gasifier 9. 
This construction of a gasification apparatus makes it possible to achieve 
any desired evaporation intensity of a cryogenic liquid virtually without 
consumption of external energy (electrical energy is necessary merely for 
controlling the valves), determined only by the pace at which the 
cryogenic liquid is fed into the gasifier.