Catalytic cracking fractionation and absorption stabilization system, and energy saving method thereof

A catalytic cracking fractionation and absorption-stabilization system of an oil refinery, wherein heat is extracted from the top of a main fractionating tower (1) by a first waste heat refrigerator (3) to serve as a refrigerator driving heat source after heat extraction so as to cool naphtha;

• rich gas (28) at the top of the main fractionating tower enters into a compressor for compression, the compressed rich gas is mixed with rich gasoline (30) discharged from the bottom of an absorber and desorbed gas (31) discharged from the top of a desorber to form a mixture, and the mixture enters into a gas-liquid separation tank (8) to reduce the phase splitting temperature therein after being cooled in a second waste heat refrigerator (7);
• a diesel oil tower (2) is arranged on the siding of the main fractionating tower (1), after the diesel oil discharged from the bottom of the diesel oil tower (2) exchanges heat with a diesel oil heat exchanger (11), the residual waste heat is used for generating power by a waste heat generator;
• in an absorption-stabilization system, two absorber intermediate heat exchangers (21) serially connected are arranged on each side edge of an absorber (9) and are serially connected with a third waste heat refrigerator (14) that is driven by the waste heat of the stable gasoline by pipelines so as to extract the heat discharged by the absorber in time during absorption and control low temperature absorption of the absorber;
• a residual pressure generator is connected to the top of a reabsorber (10) to generate power by the medium and low residual pressure of dry gas (32) at the top;
• a liquid phase at the bottom of a stabilizer (18) preheats the feedstock by a feedstock heat exchanger and is entered into the third waste heat refrigerator, a part of the discharge is extracted as product gasoline (34), and the other part enters into the third waste heat refrigerator to be refrigerated and cooled and returns to the top of the absorber from the third waste heat refrigerator to serve as circulating gasoline (35);
• and the residual pressure generator and the third waste heat generator generate electricity which is respectively conveyed into a grid by electric wires, and the power supply used by the compressor is led out from the grid by an electric wire.