Study On The Key Technology In Large-scale Industrial Reformer For Natural Gas Non-Catalytic Partial Oxidation Process

This paper, by taking the large-scale industrial reformer technology for making syngas (CO+H2) by the process of natural gas non-catalytic partial oxidation (POX) being one of the key technologies for synthetic oil production from natural gas (GTL) as the objective and the practical industrial applications of natural gas non-catalytic conversion technology as the basis, has studied both the theoretical basis and enlargement methods for such key technologies as optimized selection of process operation conditions for large-scale industrial reformer and reasonable match of burner with reformer, and put forward some implemented technical solutions in the integration of large-scale industrial reformer system employing natural gas non-catalytic POX process for setting up a GTL unit in the capacity producing a million tons of synthetic oil. A summary is as follows:1. With the study results of existing conversion process of natural gas non-catalytic POX and the analysis of its related technologies as well as the thermodynamic equilibrium calculations, the effects on the conversion results by process operation conditions in reformer have been discussed and the principles in optimized selection of process operation conditions in large-scale reformer employing natural gas non-catalytic POX put forward.2. The cold flow field in reformer has been studied by the two approaches of both large-scale experiment of cold model and numerical simulation. The study focusing on both the axial velocity and the residence time distribution of gas in the reformer have been carried out on a large-scale cold test device of 01000mm;the result compliance of experimental study and numerical simulation have been verified with the simulation calculations of cold flow field.3. The status of flow and reaction both in the existing industrial operating plant and large-scale reformer have been studied and simulated by taking the selected probability density function (PDF) model and the effect on both the flow and reaction in large-scale reformer by process conditions investigated. The simulation results show that both the flow and mix in large-scale reformer and industrial operating reformer are similar; the effect in reducing the inlet oxygen temperature is not obvious in reducing the temperature in the vicinity of reformer vault whereas increasing inlet oxygen temperature may reduce vault temperature; though increasing the steam amount may reduce the gas temperature on vault to a certain extent, yet the flame position has not shown a significant movement downward.4. By taking a steady heat-transfer theory and a sensitivity analysis it is theoretically confirmed that the key factor affecting the outer-wall temperature of reformer vault is being the thermal conductivity of Mullite insulation bricks in the various physical parameters of refractory insulation lining; a micro-structural model of porous insulation material, a micro-physical model of heat transfer and a mathematical model have been set up by taking a CFD numerical simulation for numerical simulation of micro process of heat transfer in the study of variation laws and quantitative relationship between the apparent (actual) thermal conductivity of Mullite insulation bricks and the operating temperature, hydrogen atmosphere and micro-structural scale (particle size and open porosity), and a prediction method for a apparent (actual) thermal conductivity of porous insulation material at 45-70% hydrogen atmosphere inside reformer has been proposed; the application verification of industrial operating reformer shows a better deviation (less than 6%) which may guide the arrangement engineering design of insulation lining on reformer vault; an integral physical model of heat transfer process on refractory insulation lining of reformer vault has been established and an integral simulation of heat transfer in full size with variable physical properties and multi-physical fields has been carried out. The results show that the temperature distribution features of insulation lining on large-scale natural gas reformer vault are similar to that of industrial operating plant, thus, the correctness in the design of this vault insulation lining has been verified.5. Based upon a summary of engineering practice of successful industrialization of natural gas non-catalytic POX, a large-scale process integration system of natural gas non-catalytic POX for a GTL plant in a million-ton capacity has been set up, an implemented technical scheme for the design of critical equipment and a process flows of a single train of large-scale natural gas non-catalytic conversion technology proposed. The said scheme shows that (1) a large-scale reformer produces an effective syngas (CO+H2) 147,100Nm3/h with 5 trains of natural gas conversion and 5 reformers, the yield of synthetic oil from each single reformer is 200,000t/a; (2) burner uses the same design technique for the arrangement of stream flows as that in the successful industrial operation being 4 channels of oxygen (small amount)-oxygen (large amount)-natural gas-protective steam; (3) process flows may be divided into sections of natural gas conversion, syngas heat recovery and syngas scrubbing; (4) the simulated heat calculation results of process system are basically the same as the actual operating data from industrial operating plant, the efficiency of cold gas is 84% and the total energy efficiency,99%.