CS257249B1 - A method of regenerating solutions in absorption and chemisorption processes - Google Patents

Abstract

The solution relates to a method of regeneration of absorption solutions using thermocompression in such a way that the vapors compressed by the thermocompressor are led to a suitable location in the regenerator with an appropriately lower pressure, in order to reduce the compression ratio of the thermocompressor.

Description

The present invention relates to a process for the regeneration of solutions in absorption and chemisorption processes for removing gaseous components from a gas mixture which use the scrubbing solution vapor-compression principle to increase the efficiency.

In absorption processes for removing components from a gas mixture such as CO 2, H 2 S, COS in synthesis gas plants, where the principle of thermocompression is used to increase the efficiency of solution recovery, the pressure of the recovered solution leaving the column is reduced, preferably below atmospheric pressure. This releases steam from the solution in an amount corresponding to the reduction in pressure. Together with the steam, the last part of the absorbed gas is released and the solution is cooled in proportion to the amount of released steam and the absorbed gas. The released gas vapor is compressed by the thermocompressor to the pressure at the foot of the regenerator and returns to this point where the enthalpy of the mixture is used to deepen the regeneration.

By using thermocompression, the heat consumption for regeneration can be reduced by 1/3 or more while increasing the scrubbing efficiency. The disadvantage of this method, however, is the relatively high consumption of compression work for recompressing the mixture of vapor and scrubbed gas. The drawing work can be supplied by a mechanical compressor or by a jet compressor (ejector). When driven by a mechanical compressor, the compression work is usually covered by the most valuable energy. While the jet compressor uses less energy of low-pressure steam energy, due to the very low efficiency of the ejectors (10 to 15%), the energy requirement is 5 to 7 times.

The above mentioned disadvantages are eliminated by the method of regeneration of solutions in absorption and chemisorption processes for removing gaseous components from the gas mixture, which use to increase the efficiency of the principle of thermocompression of the scrubbing solution according to the invention. one tenth of the active column height and up to six tenths of the active column height. Within this column height range, the pressure level is not as high as that at the foot of the column, so there is no need for compression work as high as the methods used hitherto and still has a sufficiently high effect of thermocompression.

The advantage of said method of regeneration of solutions in absorption and chemisorption processes for removing gaseous components from the gas mixture, which utilize the principle of thermocompression of scrubbing solution vapors, is to reduce the energy requirement for driving the thermocompressor usually by one third to one half.

1 is a schematic illustration of an embodiment of the invention; FIG. Fig. 2 shows the curve of the pressure in the regeneration column 11 (Fig. 3 shows the value of the compression work in displacing compressed vapors in the compressor 3 to different locations in column 1 and Fig. 4 shows the efficiency application of the principle of thermocompression (efficiency of the use of enthalpy of recompressed vapors) when introduced at different sites along column 2- The curve 13 then represents the ratio of the use of enthalpy of recompressed vapors to the consumption of compression work.

The pressure in the overhead column 10 has a value close to atmospheric pressure, and in the heel is about 0.13 to 0.15 MPa. The pressure in the expander 2 is reduced below atmospheric pressure to 0.07 to 0.09 MPa. The thermocompressor 2 ⁱⁿ the circuit used so far supplies steam directly to the bottom of the column 1 where the pressure is highest.

The introduction of recompressed vapors into the middle of column 2 ^will reduce compression work due to the lower back pressure. The enthalpy utilization curve of the recompressed steam 12 is initially practically a line parallel to the vertical axis (utilization approaching 100%) and only decreases strongly to zero at the top of the column.

The curve 13, which represents the result of the optimization calculation, is very flat around the maximum. Given the injection site currently practiced, curve 13, in the range of one tenth to six tenths of the column length, exhibits a compression work savings of 20 to 30% or more.

E.g. when thermocompression is used in the CO scrubbing process, with potash solution according to Figure 3 ^Z, when absorbing 8,000 m / h of CO ₂ , a pressure of 0.12 MPa is maintained at the foot of the regenerator and reduced to 0.09 MPa in the expander, thereby releasing approximately 5 000 kg of steam per hour. Recompression of this steam to 0.12 MPa requires 100 kW of power, while introducing vapors to the 32nd floor in a 64-storey column (i.e. up to 1/2 column height reduces power to 83 kW).

Claims (1)

object of the invention A method of regenerating solutions in absorption and chemisorption processes for removing gaseous components from a gas mixture which use to increase the efficiency of the principle of thermocompression of the scrubbing solution, wherein the pressure of the regenerated solution is reduced in the expander and the released steam is compressed back to the regenerator, the steam compressed in the thermocompressor is fed to the regenerator up to at least one tenth of its active height and up to six tenths of that height.