CS243382B1 - Method of hydrogen production - Google Patents

Abstract

The method of producing hydrogen from producer gas obtained by gasification of oil and tar residues by partial oxidation with oxygen and steam, preliminary combination of high-temperature and low-temperature conversion of carbon monoxide with steam and scrubbing of carbon dioxide in two stages using an aqueous solution of technical triethanolamine, consists, according to the invention, in that the content of iron and nickel carbonyls is reduced in the producer gas before entering the high-temperature conversion by saturating the producer gas with steam at a temperature of 80 to 100 °C and treating it at a temperature of 170 to 250 °C by passing it through a charge of alumina, and after conversion, the carbon dioxide is scrubbed with an aqueous solution of technical triethanolamine with the addition of an activator, e.g. 1,6 diaminohexane in an amount of 0.1 to | 15 S of weight.

Description

(54) Hydrogen production method

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The method of producing hydrogen from producer gas obtained by gasification of oil and tar residues by partial oxidation with oxygen ^and steam, preliminary combination of high-temperature and low-temperature conversion of carbon monoxide with steam and scrubbing of carbon dioxide in two stages using an aqueous solution of technical triethanolamine, consists, according to the invention, in that the content of iron and nickel carbonyls is reduced in the producer gas before entering the high-temperature conversion by saturating the producer gas with steam at a temperature of 80 to 100 °C and treating it at a temperature of 170 to 250 °C by passing it through a charge of alumina, and after conversion, the carbon dioxide is scrubbed with an aqueous solution of technical triethanolamine with the addition of an activator, e.g. 1,6 diaminohexane in an amount of 0.1 to |

With weight. I

and

243362 2

The invention relates to increasing the production of hydrogen from producer gas obtained by gasification of oil and tar residues by partial oxidation with oxygen and steam, pre-cleaning of producer gas and high-temperature and low-temperature conversion of carbon monoxide with steam with subsequent scrubbing of carbon dioxide.

The gasification of oil and tar residues by partial oxidation with oxygen and steam produces raw producer gas, which is the starting material for the production of hydrogen and for the production of synthesis gases intended for the synthesis of ammonia, methanol, oxonation of olefins, etc.

Raw generator gas emerging from pressure generators operating, for example, at a pressure of 3.5 MPa is first freed from the contained soot by pressure water washing and in the next technological stage, the contained hydrogen cyanide, hydrogen sulfide and carbonyl sulfide are removed from this gas.

It is usual that the pre-purified producer gas is freed from sulfur compounds to a value of less than 25 mg/m^.

From the thus treated producer gas, technical hydrogen and synthesis gases are obtained in the necessary proportions in the subsequent technological stages. If the proportions of hydrogen and synthesis gases produced, determined by the project and established by operational practice, are disturbed, e.g. during shutdowns, when production is limited or production of a certain product, e.g. methanol, is discontinued, it is necessary to limit the total volume of gas production from the pre-purified producer gas.

This is economically disadvantageous and therefore considerable efforts have been made to utilize the total capacity of producer gas production and increase hydrogen production while the production of syngas is limited.

However, increasing hydrogen production from additional pre-cut producer gas means a higher load on the high-temperature and low-temperature conversion section, carbon dioxide scrubbing, and methanation of residual carbon dioxide and carbon monoxide to a value of less than 10 ppm vol.

The projected and operationally adopted production volume cannot be increased simply by increasing the throughput.

It has now been found that it is possible to increase hydrogen production without major interventions in the existing equipment and without major investment-intensive modifications. The method of producing hydrogen from producer gas, obtained by gasification of oil and tar residues by partial oxidation with oxygen and steam, pre-purification, a combination of high-temperature and low-temperature conversion of carbon monoxide with steam and scrubbing of carbon dioxide in two stages using an aqueous solution of technical triethanolamine, consists, according to the invention, in that, before entering the high-temperature conversion, the content of iron and nickel carbonyls in the producer gas is reduced by min. 50% compared to the current state, when the pre-cleaned generator gas contains 3 to 5 mg/m^ Pe and 1 to 5 mg Nt/m^, i.e. 1.5 to 2.5 mg Fe/m^ and 0.5 to 2.5 mg Ni/m^, by saturating it with water vapor at a temperature of 80 to 100 °C and processing it at a temperature of 170 to 250 °C by passing it through an alumina filling, and by scrubbing the carbon dioxide in two stages with an aqueous solution of triethanolamine, to which the activator 1,6-diamlnohexane is added in an amount of 0.1 to 15% by weight.

Reducing the content of iron and nickel carbonyls in the pre-cleaned generator gas before entering the high-temperature conversion is necessary to ensure satisfactory carbon monoxide conversion throughout the entire operating cycle, e.g. with increased generator gas throughput.

months.

In the pre-cleaned generator gas, carbonyls are contained, for example, in an amount of 3 to 5 mg Fe/m^ and 1 to 5 mg Ni/m^. These carbonyls decompose in the high-temperature conversion device and penetrate the upper layers of the packed conversion catalyst, which results in a gradual deterioration of its activity, an increase in the residual carbon monoxide content in the exiting gas and an increased pressure loss of the conversion reactor.

With increased producer gas penetration, these problems will appear earlier, and this can !

lead to a shortening of the usual working cycle. These problems can be avoided if the removal of iron and nickel carbonyls is included, at least from 50. (

As has been proven, the content of iron and nickel carbonyls in installed equipment can be reduced.

intended for the purification of soot-free producer gas and for the hydrolysis of carbonyl sulfide on an alumina packing.

In the hydrolysis of carbonyl sulfide, the operation is usually carried out at 150 °C and the generator gas is treated with steam at a temperature of 75 °C and a working pressure of approximately 3.15 HPa. As has been verified, in addition to the required hydrolysis of carbonyl sulfide, a significant reduction in the contained iron and nickel carbonyls can be achieved if the operating temperature is increased from 150 °C to a temperature of

170 to 250 °C.

In order to prevent the hydrolysis of carbon sulfide from burning, the producer gas can be saturated with water vapor at a higher temperature than before, when it is usually maintained in the choke at 75 °C, at temperatures in the range of 80 to 95 °C, or even at a higher temperature.

At elevated temperatures in the range of 170 to 250 °C, the contained iron and nickel carbonyls are mostly decomposed and the solids are collected in the reactor for pre-cleaning of the generator gas and partly in the reactor in which the hydrolysis of carbonyl sulfide to hydrogen sulfide and carbon dioxide is completed.

Solid fractions from decomposed iron and nickel carbonyls separated in the reactor charge, which determine the amount of pre-cleaning of the generator gas, worsen the permeability of the process gas, and therefore it is desirable to break up the resulting crust of the bases and remove it as needed.

This reactor is taken out of operation, while the rest of the equipment remains in operation. After cooling and flushing, the deposits are removed and after possible addition of a charge, e.g. cobalt-olybdenum catalyst, possibly partially deactivated, or alumina, etc., this reactor is put back into operation.

It is possible to perform this operation, for example, 3 times a year.

Example 1

In the carbonyl sulfide hydrolysis production facility, which consists of two parallel lines, the technological regime was adjusted on one operating line so that the operating temperature was increased from the usual 150 °C to 210 °C and at the same time the dew point of the gas at a pressure of |

3.05 MPa from 75 °C to 85 °C.

and

To increase the working temperature of the gas, a new heat exchanger with a heat exchange area of 160 ^m2 was incorporated, in which the heat of the exiting gas is used to heat the entering gas. Each operating line includes two reactors with a filling suitable for the hydrolysis of carbonyl sulfide, with their main component being alumina. During the test, the filling was;

the same in both lines.

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The composition of the gas entering both lines was as follows:

what ₂ 4.2 » mol. what 45.8 * aol. »2 48.8 » aol. iaerts 1,156 formula. M 0.014 frmol. what 0.03 fr aol.

The concentration of carbonyls Po and Mi, expressed in mg Pa and Mi per £:

Fe 2.3

Ni 4.1

The impact of the change in technological regime was compared with the operating line operating in the current manner. The results achieved were as follows:

Technological mode

Existing According to the invention - process gas load (®^/N) 72,000 72,000 - working pressure (KPa) 3.15 3.15 - gas temperature at the inlet to the hydrolysis reactors (°C) 150 210 - water vapor content in the inlet gas ‘“THAT 0.013 0.024 - content of carbonyl sulfide at the outlet from hydrolysis reactors (ppm vol.) . 0.7 0.7 -process steam consumption per 1,000 m^ of input gas (kg) 41.6 55.5 -<Fe and Ni carbonyl content in the outlet gas, expressed as mg/m? Fe 2.2 0.7 None 3.95 0.4

From the analytical values it is clear that after increasing the operating temperature there was a significant decrease in the carbonyl content. With the mentioned reduction of iron and nickel carbonyls in the generator gas, it is possible to work with satisfactory results in the high-temperature conversion section throughout the operating cycle, i.e. for example 18 months.

The existing high-temperature conversion reactors were filled with 30 m^ of combined filling. Compared to the current state, the proportion of more active conversion catalysts was increased at the expense of catalysts with lower activity.

The course of the conversation and the results achieved are shown in Table 1.

Table 1

original condition reduction of Fe and Ni carbonyl content by 50% about 90 « - amount of dry gas to the converter (m^Zh) 60,000 65,000 65,000 - input CO content (% vol.) 46.5 46.5 46.5 - water vapor content m^ per m^ of input gas 1.02 to 1.12 1.00 to 1.10 0.97 to 1.1 - amount of filled catalysts (m^) Cherox 3607 5 5 5 For 6 - 10 17 20 25 Charox 3100 8 . 5 - - cartridge life and cycle considerations outages stage 1 reactor (months) 18 18 18 stage 2 reactor (months) 36 54 54 - catalyst charge price coefficient for both degrees 1 1.05 1.12 - catalyst charge price coefficient

for both stages, calculated for longer cycles (months) 1

- inlet gas temperature to reactor 1 ...degrees at the beginning of the cycle (°C) 290 at the end of the cycle (°C) 325

- CO content at the outlet of the 2nd conversion stage (* vol.) 4.0

0.93 0.62

292 292

320 330

4.0 4.0

In the low-temperature conversion section, 20 conversion catalysts were loaded into the existing reactors, as shown in Table 1. After the addition of the activator to the scrubbing liquid during the carbon dioxide flushing, the hydrogen sulfide content in the outlet gas from the first scrubbing stage decreased from the original 52 ppb to 23 ppb, which had a positive effect on reducing the irreversible deactivation of the loaded low-temperature copper-based catalyst.

When selecting the catalyst filling, it is necessary to take into account the availability and price relations of individual catalysts. Contrary to the usual situation, catalysts were filled for which an operating cycle of up to three years with sufficient operational reliability can be expected after the working period.

In the first case of intensified production, for example, the KTK 4 catalyst was filled, which, due to the lower zinc oxide content, has lower resistance to catalyst poisons.

After 18 months of operation, 40% of the catalyst charge was replaced with the same amount of ICI 52-1 catalyst and, after its reduction, the combination was operated for another 18 months. In the second case of intensified production, ICI 52-1 catalyst was charged, which allowed operation for 36 months.

The course of the conversation and the results achieved are shown in the following table 2.

Table 2 original state intensified operation case 1 case 2 amount of dry gas into the converter

(m^/h) 60 240 65,060 65,060 input CO content (* vol.) 5.42 5.42 5.42 water vapor content m^ to m^ inlet gas 0.28 0.30 0.26 catalyst charge (m^) C 18 HC 20 - - NTK 4 - 20 (12) - ICI 52-1 - - (8) 20 monthly filling life 24 36 36 price coefficient of catalyst fillings 1 0.9 1.17 price coefficient of catalyst fills calculated per duty cycle 1 0.65 0.78 output CO content at the beginning and at end of cycle (* volume) 0.37 to 0.41 0.38 to 0.46 0.36 to 0.41 To intensify hydrogen production it is necessary to increase working capacity when filling oxygen- carbon dioxide, which is carried out in two stages. It was found that with an increase in work

capacity is achieved by adding to the used 30 to 35% aqueous sprout of technical trietano

243382 6 lamina is added with an activator. A suitable activator is, for example, 2,6 diaminohexane added in an amount of 0.1 to 15% by weight. For practical application, it is important that the efficiency of the washing liquid with the activator allows for a reduction in the amount of washing liquid while maintaining approximately the same hydrodynamic load on the absorbers even with increased hydrogen production.

For operational applications, it is also required that the added activator does not increase the corrosive effect of the circulating washing solution, or that the corrosive effect of the circulating washing solution is reduced. Tests have shown that these two requirements are met by, for example, 1,6 diaminohexane.

Claims (1)

P & SSUSX OF THE INVENTION A process for producing hydrogen from a generator gas obtained by gasification of petroleum and tar residues by partial oxidation with oxygen and steam, pre-treatment, by combining high temperature and low temperature carbon monoxide carbon monoxide and carbon dioxide scrubbing in two stages using an aqueous solution of technical triethanolamine. of gas before entering the high temperature conversion reduces the carbonyl content of iron and nickel to 1.5 to 2.5 mg Fe / m 2 and 0.5 to 2.5 mg Ni / m 2, so that the amount of carbonyl is reduced. the pre-refined generator gas is saturated with water vapor at 80 to 100 ° C and treated at 170 to 250 ° C by passing through an alumina charge and after conversion the carbon dioxide is scrubbed with an aqueous solution of technical triethanolamine with the addition of an activator such as 1,6 diaminohexane in an amount of 0.1 to 15% by weight.