Reverse osmosis desalination device having improved energy recovery method

The present invention relates to a reverse osmosis desalination device having an improved energy recovery method and, according to one embodiment of the present invention, the reverse osmosis desalination device is a reverse osmosis desalination device comprising: a desalination module 215; a high-pressure pump 225 for providing reverse osmotic pressure to the desalination module 215; a cylinder block 208 for recovering the energy of a concentrated liquid (Q 300 ) emerging from the desalination module 215; a control valve 214 for alternately connecting the desalination module 215 to cylinders 206 and 207 of the cylinder block 208; and a pre-processing unit 202 for salt water 201 intended for desalination, and, here, the control valve 214 is operated by means of the pressure of the concentrated liquid (Q 300 ) emerging from the desalination module 215, the concentrated liquid (Q 300 ) emerging from the desalination module 215 alternately flows in towards the sides of the cylinders 206 and 207 where there is no shaft, the salt water (Q 100 ) intended for desalination emerging from the pre-processing unit 202 alternately flows to the sides of the cylinders 206 and 207 where there is a shaft, and salt water (Q 100 ) that has recovered the energy of the concentrated liquid (Q 300 ) is introduced under pressure to a high-pressure line 220 alternately from the sides of the cylinders 206 and 207 where there is a shaft, and in this way the salt water (Q 100 ) intended for desalination emerging from the pre-processing unit 202 increases in pressure just by recovering the energy of the concentrated liquid (Q 300 ), without any other pressurizing means, and can merge into the flow of high-pressure salt water (Q W ) intended for desalination emerging from the high-pressure pump 225.