This paper studied the thermal effect resulting from the adsorption of natural gas on both charge and discharge on an absorbed storage system using a phase change material (PCM) as heat exchanger. A kind of organic PCM whose phase change heat is 153 J/g, measured by DSC,consisting of decanoic acid and lauric acid was prepared. The PCM was used to control the heat effect during the adsorption and desorption of natural gas. By adding the volume ratio of 6.10 % of the PCM into the adsorption tank, the temperature change can be reduced 21.8°C during adsorption and can be increased 22.7°C during desorption. Meanwhile, the delivered natural gas volume was increased 39.4 % with the use of the PCM compared to the case without PCM for a 0-3.5 MPa of pressure swing. Application of this kind of cheap PCM in the adsorption tank is an effective method to reduce the adverse effects of adsorption heat and thereby enhance storage capacity and delivery.

Adsorption of each component of natural gas on adsorbent prepared from petroleum coke was studied. At 25°C and 3.5 MPa, adsorption capacity of the components of natural gas are as follows: C 3 H 8 , H 2 S(0.980) > CO 2 (0.691) > C 2 H 6 (0.160) > CH 4 (0.136) > N 2 (0.096) (g/g). For natural gas, adsorption capacity is 145.2 (mL/mL) and delivery capacity is 105.7 (mL/mL). One equation between adsorption capacity and boiling point of adsorbed gas was firstly generalized. The adsorption capacity of different component like O 2 , N 2 , CH 4 , C 2 H 6 , CO 2 , H 2 S on adsorbents were predicted using the equation. The results fit well with the experimental data. The equation has significance in predicting the adsorption capacity for any component of natural gas. Charge-discharge tests were conducted 10 times, the result indicates that natural gas has significantly worse reversibility in adsorption and desorption in the adsorbent than that of CH 4 . The contents of the components after 10 charge-discharge show that the adsorption capacity drop of natural gas is due to the irreversible adsorption of heavy or polar components like C 3 H 8 , H 2 S.

No abstract