RU2243147C1 - Hydrogen generator for transport power plant - Google Patents

Abstract

FIELD: power equipment; generation of hydrogen at stationary plants and on transport facilities.

SUBSTANCE: proposed hydrogen generator works on hydrolysis with hard reagent and includes container with solid reagent placed in reaction vessel; it is provided with hydrogen supply line, liquid reagent supply line, heat exchanger for discharge of reaction heat and starting liquid heater. Hydrogen generator is also provided with bypass reservoir communicated with reaction vessel in its lower portion through shut-off member; volume of this reservoir exceeds volume of liquid reagent; it is provided with supercharging line; liquid reagent supply line is connected to bypass reservoir where starting heater is located and liquid temperature sensor; solid reagent is distributed over height of liquid reagent column. Reaction vessel and bypass reservoir are made in form of two coaxial cylindrical vessel inserted one inside other; reaction vessel is located inside bypass reservoir.

EFFECT: automatic stabilization of process; increased speed of response.

1 dwg

Description

The invention relates to power equipment and can be used to produce hydrogen both in stationary installations and in transport.

The generator is a chemical reactor that produces hydrogen by hydrolysis, i.e. decomposition of water. For this, a solid reagent is used, i.e. the hydrolysis reaction is heterogeneous in nature - occurs on the surface of a solid. It is assumed that the hydrogen thus obtained is subsequently used as fuel for power plants (EC) on fuel cells (FC). In addition, hydrogen can be used, of course, in other areas, for example, in metal cutting, welding, etc.

Previously, in the latter case, acetylene generators of the GNV-1.25 and GVR-1.25 types were used mainly [1]. A heterogeneous hydrolysis reaction was also used, and calcium carbide served as a solid reagent. This technical solution is taken as an analog. Its disadvantages include the following:

- synthesized acetylene is not suitable for oxygen-hydrogen fuel cells and needs further decomposition to hydrogen. This significantly complicates the design of the EU and reduces its efficiency. The low weight hydrogen content in such generators makes them unsuitable for transport;

- during the operation of acetylene generators an insoluble precipitate (lime) is formed, the accumulation of which limits the time of continuous operation of the generator, worsens its overall weight characteristics. Removing sludge from the reactor requires additional energy consumption, complicates the design of EU, reduces its efficiency;

- a solid reagent (calcium carbide) is a material whose long-term storage is quite difficult and unsafe, because it is very hygroscopic and when it absorbs moisture from the air, it releases acetylene.

The disadvantages of the analogue should also include:

- insufficient depth of gas flow control, which is due to the fact that in the vertical reaction vessel the solid reagent cartridge is placed horizontally;

- a large temporary inertia, due to the fact that the liquid is not completely and rather slowly displaced from the solid reagent cassette;

In addition, the disadvantages of the analogue are:

- lack of temperature adjustment (although the temperature greatly affects the reaction);

- non-optimal overall layout of the design, which is a disadvantage from the point of view of transport, especially if the dimensions of the generator are large.

Closer in essence is a hydrogen generator designed to power a fuel cell based on a fuel cell used in an underwater vehicle [2]. This reactor also uses a hydrolysis reaction, and metal hydrides (i.e. metal compounds with hydrogen) are used as a solid reagent. The generator includes a reaction vessel into which a “chamber” with metal hydride is placed, a heat exchanger for removing heat of reaction, a device for mixing water in the reaction vessel (located inside the latter) and a line for supplying water to the reactor and removing hydrogen from the reactor. In this case, to improve the overall weight and weight characteristics of EU, hydrides of light metals are used, which are very expensive (LiH, BeH ₂ ...). This significantly increases the cost of hydrogen produced and is a significant drawback of the generator [2], adopted in this case as a prototype.

In addition, the disadvantages of the prototype include the following:

- tough flow characteristic of the generator, due to the strong dependence of the rate of the chemical reaction on temperature and, as a result, the difficulty of stabilizing the operation of the generator;

- the energy intensity of the thermoregulation system of the generator, due to the fact that when adjusting the flow rate, it is necessary to change the temperature of the whole substance in the reaction vessel, and, in addition, to ensure uniform temperature throughout the reaction volume;

- the disadvantage of the design of the generator is also thermal inertia, which complicates its use in transport power plants.

The latter is due to the fact that for the generator to operate in stationary mode, it is necessary to maintain a certain temperature of solid and liquid reagents. If there are a lot of them, maintaining the temperature regime of the generator is technically complicated and requires significant energy consumption (for example, the operation of mixing devices). In addition, the transient modes of operation of such a hydrogen generator take a lot of time in this case, since it requires a temperature change of significant masses of substances having a relatively low thermal conductivity (water, metal hydrides). For transport tasks, this is a huge drawback.

The objective of the proposed solution is to develop a hydrogen generator with a “softer” flow characteristic, automatic stabilization of the mode and increased speed. In addition, the generator should be as compact as possible to be used in vehicles.

The essence of the proposal is as follows.

In addition to adjusting the course of the reaction (i.e., the productivity of the generator) by temperature, the area of the solid reagent also changes in the proposed solution. Moreover, in comparison with thermal regulation, the effect of the area of the solid reagent is much more “soft”. The latter is caused by the fact that the hydrogen flow rate is proportional to the area of the reacting solid component and can vary quite smoothly, and it depends on temperature exponentially (exp (-1 / T)), i.e. substantially nonlinear. This circumstance allows you to adjust the performance of the generator in two stages: initially coarse adjustment - changing the temperature of the reagents, and the next smooth - changing the area of the solid reagent immersed in the liquid.

To implement this principle, a hydrogen generator of a transport power plant operating on hydrolysis with a solid reagent and containing a container with a solid reagent, placed in a reaction vessel with a hydrogen supply line, a liquid reagent supply line, a heat exchanger for removing reaction heat and a starting liquid heater, was introduced a bypass vessel communicating in the lower part with the reaction vessel through a locking element having a volume exceeding the volume of the liquid reagent and equipped with a charge line VA, and the liquid reagent supply line is connected to a bypass vessel in which the starting heater is located, as well as a liquid temperature sensor, while the solid reagent is distributed along the height of the liquid reagent column.

The reaction vessel and the bypass vessel are made in the form of two coaxial cylindrical vessels embedded in each other, the reaction vessel being placed inside.

A diagram of such a generator is given in the figure, where it is indicated: 1 - a container with a solid reagent; 2 - reaction vessel; 3 - line for the issuance of hydrogen; 4 - line supply of liquid reagent; 5 - heat exchanger for removing heat of reaction; 6 - starting fluid heater; 7 - bypass capacity; 8 - boost line; 9 - locking element; 10 - liquid temperature sensor.

The generator operates as follows. On the supply line of the liquid reagent (4), it is collected in the bypass tank (7) and heated there with a starting heater (6). The locking element (9) is thus closed. After reaching the required temperature (controlled by the temperature sensor (10)), the starting heater is turned off, and the locking element (9) is opened. The liquid from the transfer tank (7) flows into the reaction vessel (2), where a container with a solid reagent (1) is vertically placed. In this case, the container (1) is completely covered with liquid.

A chemical reaction begins with the release of hydrogen and heat, which is removed using a heat exchanger (5). Generator performance is regulated in two steps. First, roughly - by setting the appropriate temperature in the reaction vessel, and then more precisely - by adjusting the height of the liquid in it, i.e. depth of immersion in a liquid container with a solid reagent (1). The latter is achieved by changing the pressure in the overflow tank (7), for which the boost line (8) serves.

After setting the required liquid level in the reaction vessel (2), the locking element (9) can be closed. It is also possible to leave it open. In this case, at a constant pressure in the overflow tank, the generation mode is automatically stabilized, i.e. generator performance. With an increase in the pressure of hydrogen in the reaction vessel (2), the liquid is displaced from it into the bypass vessel (7), the area of the reacting solid component decreases, and the consumption of released hydrogen decreases. The pressure in the reaction vessel (2) drops until it reaches the previous value.

When the pressure in the reaction vessel (2) decreases, the liquid reagent, on the contrary, enters it from the bypass vessel (7). The liquid level rises and the wetted area of the solid reagent increases. As a result, the consumption of generated hydrogen also increases.

Thus, auto-stabilization of the hydrogen pressure in the reaction vessel (2) occurs according to the value of the reference pressure in the bypass vessel (7) (taking into account the difference in liquid levels in these communicating volumes). Moreover, since the solid reagent is placed uniformly along the height of the reaction vessel (2), the ratio between liquid and solid reagents remains unchanged at any liquid level in the reaction vessel (2).

When the generator stops, the pressure in the bypass vessel (7) decreases, the liquid from the reaction vessel (2) flows into this vessel (7), and the solid reagent is isolated in a hydrogen atmosphere. Hydrogen evolution ceases. When the generator is restarted, the liquid remaining in the transfer tank (7) is heated again, which reduces the time the generator takes to the mode.

To reduce the size of the hydrogen generator, the reaction vessel (2) and the bypass vessel (7), it is advisable to perform in the form of two coaxial cylindrical vessels, nested in each other, and the reaction vessel is placed inside the bypass vessel.

Thus, the proposed technical solution allows you to create a compact hydrogen generator that works on the hydrolysis reaction, having a deep degree of adjustment, soft flow characteristics, high speed and able to work in auto stabilization mode. All this makes it advisable to use such a hydrogen generator in transport.

LIST OF REFERENCES

1. V.V. Rybakov. Textbook gas welder. - M., MASHGIZ, 1956

2. “Hydrogen generation by hydrolysis for a power plant based on underwater fuel cells”. Patent. 5372617, USA, 1994.

Claims (2)

1. A hydrogen generator of a transport power plant operating on solid reagent hydrolysis and containing a container of solid reagent, placed in a reaction vessel having a hydrogen supply line, a liquid reagent supply line, a heat exchanger for removing reaction heat and a starting liquid heater, characterized in that the composition of the generator introduced a bypass tank, communicating in the lower part with the reaction vessel through a locking element having a volume exceeding the volume of the liquid reagent and equipped with a line above blow, and the line for supplying the liquid reagent is connected to the bypass tank, which houses the starting heater, as well as the liquid temperature sensor, while the solid reagent is distributed along the height of the column of the liquid reagent. 2. The hydrogen generator of the transport unit, characterized in that the reaction vessel and the bypass vessel are made in the form of two coaxial cylindrical vessels embedded in each other, and the reaction vessel is placed inside.