Two, background technology: known gas treatment regeneration method of active carbon has ramp regeneration, pressure swing regeneration, displacement regeneration, purge several classes of regeneration, to adsorbate is volatile nonpolar organic matter charcoal absorption system, usually using heats up and feed carrier gas purges in conjunction with regenerating, general earlier carrier gas (water vapour or air) directly the heating, make it pass through active carbon layer again, active carbon is regenerated, the characteristics of these class methods are that the heat transfer direction is to nexine from the active carbon top layer in the regenerative process, the mass transfer direction is then opposite, cause resistance to mass tranfer to increase like this, influence mass transfer effect, and then the recovery time long (30~100min), in addition, hot-air and water vapour heated up earlier to regenerate makes energy consumption higher, and heat utilization efficiency is lower.
The result of practical application in industry shows that the deficiency that existing above-mentioned each renovation process exists is:
1) the charcoal proportion of goods damageds are higher relatively: 3~15%;
2) recovery time is longer: 30~100min;
3) charcoal absorption capacity restoration rate is not high;
4) regenerative process energy consumption height;
5) reclaim equiment complexity;
6) regeneration times is too much, and the deterioration of active carbon is serious;
7) regeneration cost shared proportion in whole absorbing process is very big.
Microwave heating technique successful Application in fields such as food processing, dry materials, chemical reactions, compared a lot of advantages with traditional mode of heating, as energy utilization rate height, firing rate fast (be traditional heating mode 1/tens to 1/tens in addition shorter).It is reported that microwave has in water treatment active carbon regeneration field as the thermal source regenerated carbon and uses, but still is in the starting stage, be used for regeneration gas processing active carbon and then all belong to blank both at home and abroad.
In view of all many-sides of traditional active carbon method need to improve, heating using microwave can be used for the regeneration of water treatment active carbon, and the gas treatment active carbon particularly carries the different of volatile nonpolar organic matter active carbon and water treatment active carbon regenerative process, has impelled formation of the present invention.
Three, summary of the invention: purpose of the present invention is intended to utilize heating using microwave energy utilization rate height, fast, the homogeneous heating of firing rate, thermograde is little, heat simultaneously the inside and outside when being used for active carbon regeneration, internal temperature is a little more than external temperature, heat transfer direction and characteristics such as the mass transfer direction is consistent, microwave is directly acted on active carbon as thermal source, improve traditional thermal regeneration active carbon method, set up a kind of new volatile nonpolar organic matter regeneration method of active carbon.
The present invention relies on following technical scheme to realize.
1. Fig. 1 is a process chart of the present invention.After preliminary treatment, control its flow and pressure from the carrier gas that the carrier gas source of the gas comes out, enter the active carbon regeneration reactor that is positioned at microwave applicator, to carrying processings of regenerating of a volatile nonpolar organic matter active carbon, the active carbon that obtains regenerating, exit flow recycles through cooling.
The alternative condition of carrier gas be in the micro wave regeneration process not can with adsorbate and active carbon generation chemical reaction, nitrogen or inert gas are used in the regeneration of carrying volatile nonpolar organic matter active carbon, in addition, carrier gas source also provides power, makes carrier gas possess certain pressure to pass through regenerative system; The carrier gas pretreatment unit comprises silica gel and activated-charcoal column, and its effect is to utilize silica gel and active carbon to the suction-operated of moisture content and other impurity, removes moisture content and impurity in the carrier gas; Flow and pressure control section are that the control carrier gas is passed through regeneration reactor with the required flow velocity of technology; Microwave applicator is that microwave power decides according to amounts of activated carbon for active carbon regeneration provides certain frequency and required microwave radiation; The material of active carbon regeneration reactor must guarantee the penetrable and energy high temperature resistant (more than 800 ℃) of microwave, the most handy quartz glass; Exit flow after micro wave regeneration is carrier gas and adsorbate mixed airflow, must handle through cooling, and the present invention lowers the temperature by water cooling heat exchanger to reclaim the adsorbate of condensation.
2. process conditions
The important indicator that active carbon regeneration generally needs to consider is the adsorption capacity and the active carbon proportion of goods damageds of desorption rate, regenerated carbon, through experimental studies have found that the principal element (process conditions) that influences these several indexs has microwave power, amounts of activated carbon, recovery time and flow rate of carrier gas etc.
Each process conditions to desorption rate to influence rule as follows:
1) desorption rate is influenced size and be followed successively by amounts of activated carbon, microwave power, microwave irradiation time, nitrogen linear velocity;
2) amounts of activated carbon increases the raising that helps desorption rate; The increase of microwave power helps the raising of desorption rate; Recovery time, long more desorption rate was high more; The nitrogen linear velocity is not remarkable to the influence of desorption rate.
Each process conditions to the regenerated carbon adsorption capacity to influence rule as follows:
1) size that influences to adsorption capacity is followed successively by amounts of activated carbon, nitrogen linear velocity, microwave power, microwave irradiation time;
2) adsorbance of the big more regenerated carbon of amounts of activated carbon is big more in the regeneration; The big more regenerated carbon adsorbance of microwave power is high more; The length of recovery time is little to the influence of regenerated carbon adsorbance, but growth in time, the regenerated carbon adsorbance also increases thereupon; Flow rate of carrier gas is greater than or less than the raising that 0.4m/s helps the regenerated carbon adsorbance.
It is big more that each process conditions is embodied in microwave power to the influence of the active carbon proportion of goods damageds, and the loss of active carbon is big more; The excessive too small active carbon loss increase that all can make of carrier gas line speed; Amounts of activated carbon is big more, and the active carbon loss is big more.
Technological condition of regeneration according to above-mentioned rule optimization is: microwave power/amounts of activated carbon 70~90W/g active carbon, flow rate of carrier gas 0.1~0.3m/s, recovery time 6~7min.
3. regenerative process can be calculated the residual quantity of adsorbate on the active carbon of any time in the micro wave regeneration process with following formula among the present invention
Formula 1) residual quantity of adsorbate on q in---any time active carbon, kg adsorbate/kg active carbon;
q
0---the adsorbance of the active carbon when regenerating, kg adsorbate/kg active carbon;
T---the time, s;
M
C---quality of activated carbon, kg;
Formula 2) U---flow rate of carrier gas in, m/s;
F---regeneration reactor cross-sectional area, m
2
M---adsorption molecule amount;
Pv---adsorbate saturated vapour pressure, mmHg;
LogPv=-0.05223A/T+B, A wherein, B is a constant, T is a t active carbon temperature (K) constantly, is calculated by active carbon intensification equation.
Find the solution 1) boundary condition and the primary condition of formula be
t=0,q=q
0;
t=t
M,q=0;
q≤q
0
T
MBe adsorbate evaporation concluding time, s.
Adsorption density is calculated by following formula in any time exit flow
-dq/dt=C
T·Q 3)
Q in the formula, t---meaning is the same;
Q---carrier gas flux, m
3/ s;
C
t---the mean concentration of adsorbate in the dt time, kg/m
3
Formula 3) be an ODE, owing to the time is 0 o'clock, q=q
0, substitution 1 again) in the q expression formula, can solve C
TWith the relation of t, promptly the toluene exit concentration over time.
4. technical indicator of the present invention and characteristic
The present invention can reach following technical indicator:
Recovery time: 6~7min; Adsorbance recovery rate 85~110%; The charcoal proportion of goods damageds<9%; Total energy consumption (power consumption)≤9.07kwh/kg active carbon.
Show that with renovation process comparative result commonly used the present invention has following technological merit:
1) technology is simple, and the recovery time is short, is 1/2~1/140 of conventional regeneration method;
2) absorption property of regenerated carbon recovers good; Because toluene has dilating effect to the active carbon hole when sharply evaporating, regenerated carbon adsorption rate even can surpass fresh charcoal;
3) not consumption of calorie, steam of regenerative process, energy consumption is far below the method beyond the forced electric discharge reactivating, owing to do not consume extra heat and steam, so technology is simple, easy and simple to handle;
4) can reclaim adsorbate, because regeneration adsorbate purity height does not have other accessory substance, it is very high to reclaim product purity, because microwave energy can not cause the disconnection of chemical bond, so when being applied to other organic adsorbate, can not producing because of organic matter yet and decompose the secondary pollution that produces.