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Dioxin

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How the Dioxins reduce in the garbage furnace by combusted with coal

A. Main Reason
B. Experiment
C. Result
     Coal effect on fore-produce PCP
     Results of the 3-stage fluidized bed
     The Results of the 1MW Fluidized Bed

A. Main Reason

HCl is common in the flue gas coming from the garbage furnace. When there is Cu existed, the Deacon Reaction will take place and the HCl will change into Cl2. The existent of Cl2 will promote Dioxins production. The reaction formula as follows:

When the garbage furnace operating with the coal, there will be SO2 existed. SO2 will react with Cl2 and H2O and change into HCl and SO3. This reaction will reduce the Cl2, so do the Dioxins. The reaction formula as follows:

In another way, the catalyst Cu in formula 1.3 will be poisoned by the SO2, and it will change into CuSO4 with less active. The reaction formulas as follows:

Because of the catalyst posioned and the less Cl2 contain in the flue gas, so the Dioxins is less than the normal garbage furnace which don’t combusted with coal.

B. Experiment

All the experiments are taking place in small pipe furnace, 3-stage fluidized bed experimental platform, and 1MW fluidized bed furnace. The fuel analysis is in Table 1.1.

Table 1.1 Fuel Analysis

Furnace	Sample Name	Mt	Aar	Car	Har	Nar	Sar	Oar	Qb,y (kj/kg)
Pipe Furnace	Shenfu Coal	6.6	9.56	66.34	3.61	0.95	0.38	12.6	26216
Fluidized Bed	Yanzhou Coal	1.84	18.1	65.88	4.06	1.27	0.7	9.0	25757
	Waste Paper	74.62	1.59	15.86	1.98	0.43	0.05	5.47	6196.9
	Mixed Garbage	3.24	0.43	47.62	6.02	0.68	0.07	41.9	17700
	Mixed Coal	3.82	46.32	38	2.2	0.74	3.88	5.0	12644
1MW Fludized Bed	Garbage	40	29.8	11.46	2.7	0.8	0.04	15	4182
	Huainan Soft Coal	8.85	21.37	57.42	3.81	0.93	0.46	7.16	20467
	Waste Paper	74.62	1.59	15.86	1.98	0.43	0.05	5.47	6196.9

C. Result

1. Coal effect on fore-produce PCP

The experiment results are in the table 1.2 and graph 1.1. The higher ratio between PCP and coal is, the more Dioxins produced.

Table 1.2 PCP Reults (ng/g PCP)

Condition	1	2	3	4	Coal=0
S/Cl ratio	1.310	1.305	2.391	2.336	/
PCP(g)	0.0498	0.1001	0.0500	0.0504	0.0508
Coal(g)	0.1255	0.2512	0.25	0.245
PCDDs	13494.78	3856.79	2873.10	1864.30	33979
PCDFs	4576.68	1561.84	370.023	1134.79	31230
Total	18071.47	5418.63	3243.12	2999.09	65210
Limited %	72%	90%	95%	95%	/

Graph 1.1 The coal's effect on the PCP

2. Results of the 3-stage fluidized bed

The combust temperature of the 3-stage fluidized bed is 800c. The fluidize quantity is 1.4m3/h. The weight ratio between coal and PVC is 1:2. The sulfur concentration in the coal is 3.88%. The ratio between waster paper and coal is 8:2, and the ratio between garbage and coal is also 8:2.
The graph 1.2 is the results of the PVC combustion. Compared with the combustion of the coal and PVC mixture, the former create more Dioxins.

Graph 1.2 The Dioxins Creating in PVC Combustion

When the coal added in the waste paper combustion, the Dioxins also were limited. The results are in the graph 1.3.

Graph 1.3 The Dioxins Produced in the Waste Paper Combustion

The results of the coal and garbage mixture combustion is in the graph 1.4.

Graph 1.4 The Dioxins Produced in the Garbage Combustion

3. The Results of the 1MW Fluidized Bed

Table 1.3 1MW Fluidized Bed Exhaust

	Coal:MSW	T/C	PCDD/Fs	I-TEQ
1	0.37:0.63	818	705.36	2.263
2	0.28:0.72	695	1129.03	2.066
3	0.45:0.55	870	1083.64	2.523
4	0.26:0.74	917	1560.806	2.854

The graph 1.5 is about the relationship between the temperature and Dioxins. As the temperature increase so does the Dioxins' toxicity.

Graph 1.5 Temperature and the Dioxins

The graph 1.6 and graph 1.7 is about the CO and coal effect on the Dioxins producing. The less coal in the mixture fuel, the more Dioxins produced.

Graph 1.6 CO Effect

Graph 1.7 Coal Mixed with Garbage Effect