Institute of Clean Coal Technology(ICCT), Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, East China

Transcription

1 Dynamic Simulation of Opposed Multi-Burner Coal-Water Slurry Gasification System Zhenghua Dai*, Junyu Yang, Chao Li, Guangsuo Yu, Fuchen Wang Institute of Clean Coal Technology(ICCT), Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, East China University of Science and Technology (ECUST), Shanghai , China

2 Content The introduction The dymamic model of Opposed Multi-Burner (OMB) Coal-Water Slurry Gasification System Dynamic Simulation of Online Reset Process(ORP) operation Dynamic Simulation of gasification temperature Control Conclusions

3 1. The introduction The research field of dynamic system simulation The dynamic characteristic of unit equipment The optimization of process parameter, especially for whole system intergration The design and validation of control scheme, especially for the whole system control The operation early-warning and acident repeat Operation Train System (OTS)

4 The review of dynamic simulation of coal gasification system Gasifier Control lsystem Robinson and Luyben GE Y Rory GE N Casella Shell Y Lee Shell N Flexible RNM for a one- or two-stage gasifier with syngas cooling (Rory ) Flowsheet for approximate model(robinson and Luyben)

5 2. The dymamic model of Opposed Multi-Burner Coal- Water Slurry Gasification System Cross section view of the Schematic of gasification process with OMB CWS gasifier OMB CWS gasifier

6 reactor network model (RNM) based on RTD Heterogeneous Reactions (the unreacted-core core shrinking model) Simplified Flow Field (1500TPD, 6.5MPaG gasifier)

7 Results Validation Residence Time Validation Particle and gas state Comparison of gas and particle RTD transition diagram for Markov for RNM and CFD Chain Comparison of industrial data and the steady-state state simulation results Item Temperature ( ) Carbon Mole fraction (dry basis) (%) Consumption 1) conversion m (Coal) (kg) V (Oxygen) (%) H 2 CO CO 2 Nm 3 Industrial data Simulation results

8 Dynamic model of fomb gasification system The steady model is transformed into the dynamic model which adopts pressure driven solution in UniSim software(hysis).

9 Simplified valve parameters of the pipe resistance (1500TPD, 6.5MPaG) Item Stream Flow Resistance Valve opening (kpa) (%) VLV-1-1/2 CWS 35.66m 3 /h VLV-2-A/B/C/D CWS 17.85m 3 /h VLV-3-A/B/C/D Oxygen 8490Nm 3 /h VLV-4 Grey water kg/h VLV-5 Black water kg/h VLV-6 Syngas kg/h VLV-7 Syngas kg/h VLV-8 Syngas kg/h

10 Parameters of the PID controllers Controller Description Kc I(min) Arrange Type Action FC-C-1/2 Control the flow of CWS m 3 /h Auto Reverse FC-O-A/B/C/D Control the flow of oxygen STD_m 3 /h Auto Reverse PC-1 Control the outlet pressure kPa Auto Direct PC-2 Control the downstream pressure kPa Auto Direct LC Control the quench chamber level % Auto Direct

11 3. Dynamic Simulation of Online Reset Process (ORP) operation The specific online reset process (ORP) is an own operation for the OMB CWS gasifier. A couple of shut-off burners will be put into operation under the high pressure when the other couple of burners are still running.

12 operation steps of the ORP (1). Burner-C and burner-d are joined into the gasifier in 40th second. The setup (SP) value of CWS flow rate in burner-c and burner-d is set as m3/h after 2 seconds. (2). The SP value of the CWS and oxygen flow rate is separately set to increase 0.4 m3/h and 189 Nm3/h every 60 seconds. The SP value of CWS flow rate can be ordered to a desired point after 9 minutes. Outlet pressure of the gasifier is adjusted automatically by the PC-1 and PC-2. During the process of syngas increasing, the SP value of PC-1 and PC-2 is set as 5300 kpa. (3). The SP value of gasifier pressure is set to increase 100 kpa every 60 seconds. After the completion of the procedure, the SP value for the outlet pressure is 5800 kpa. During the pressure increasing, PC-2 will be set in manual and its valve opening is fixed. The outlet pressure of gasifier will be regulated by PC-1. When the valve opening of the PC-1 is 0 percent, the PC-2 will be set in auto to conduct the gasifier pressure.

13 The dynamic simulation result of the ORP operation Coal water slurry pump-1(a) and -2(b) Pressure control PC-1 (a) and PC-2 (b) Oxygen flow FC-O-A(a) and FC-O-C(b)

14 Response results of the inlet and outlet conditions in the ORP

15 4. Dynamic Simulation of gasification temperature Control Gasification temperature control sheme Parameters of the PID controllers Controller Description Kc I(min) Arrange Type Action FC-O-A/B/C/D Control the flow of oxygen STD_m 3 /h Cascade Reverse O/C-A/B/C/D Control the oxygen-coal ratio Nm 3 /m 3 Cascade Reverse TC-A/B/C/D Control the outlet Auto Reverse temperature

16 Dynamic Simulation of Temperature Control with CWS Concentration Disturbance Coal water slurry Temperature control

17 Oxygen-coal ration Oxygen flow

18 5. Conclusions Based on the flow field analysis and the particle and gas RTD, a reactor network model (RNM) of the OMB CWS gasifier with detailed reaction kinetics is established. The steady-state state model is then transformed into the dynamic model which h adopts pressure driven solution. In the dynamic simulation of the ORP, the gasifier pressure will make a great effect on the operation conditions. With the gasifier pressure increasing during the ORP, the oxygen flow rate will be changed by the transformation of the pressure differential at both ends of the valve. The peak deviation of the temperature is about 33 and that of the pressure is 106 kpa. A temperature control strategy, which selects the oxygen flow rate as the control object, is established to investigate the dynamic response for the disturbance of the CWS concentration. ti The self regulation time to the 1.5% step changes for the CWS concentration is about 34 seconds in the OMB CWS gasifier. The peak deviation of the temperature is about

19 Future: The dacay of the controllers and PID parameters study The validation of ORP operation The dynamic simulation of other operation process The dynamic optimization of gasification system Challenge: The dynamic model for the gasification system The gasifier temperature measurement and its decay

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