Plan for emergency maintenance project of 80,000 tons/year system:

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I. Main objectives: 1. To eliminate the severe blockage in the fire-tube boiler (which is currently at 1200 mmH2O), increase the acid production per shift, and delay the annual major maintenance until December. 2. Eliminate the current surge phenomenon of the main fan fundamentally. 3. Take this maintenance opportunity to address some minor issues. II. Preparations before parking: 1. Before parking, try to empty the large melting pool and the sulfur pump tank as much as possible, so as to facilitate the removal of any sulfur slag that has settled at the bottom during this maintenance work. 2. Preparation of materials before parking: tools for salvaging sulfide slag, corundum protective sleeves, high-temperature refractory materials and refractory cement, tools for cleaning the flue pipes (such as high-pressure washers), nails for removing the second-stage catalyst, firewood, and 3 tons of diesel. Have ample supplies of liquid alkali and other materials needed for exhaust gas absorption. 3. Analyze whether there is any air leakage in the two heat and cold exchangers to determine the maintenance tasks: (If there is no leakage, only the hot-air blowing system needs to be used; otherwise, the system must be converted to cold-air blowing mode in order to seal the leaks before the exchangers can be maintained.) (Maintenance has been decided against.) III. How to shut down and start up the system? How to shut down the system: Scheduled shutdown time: 8:00 AM on August 6, 2007. 1. For systems with a capacity of 80,000 tons, try to empty the crude melt pool and the sulfide pump tank first; after stopping the sulfide supply, blow dry hot air into the system for 5–6 minutes to facilitate maintenance. 2. Open the manway blind flanges at the boiler outlet smoke box and at the inlet, simultaneously close the high-temperature disc valves, and seal off the pipes leading to the converter using plug blind flanges. Use dry air to blow air through only the sulfur incinerator and the boiler in order to cool them down, reducing the temperature to below 150°C for easier maintenance of the boiler. (The cooling time is estimated to be around 12 hours.) ) 3. The rest shall be shut down in accordance with the system shutdown procedure. How to operate: 1. Introduce the steam from the 40,000 tons/year system into the 60,000 tons sulfonation tank for sulfonation ； 2. Determine whether to use firewood based on the temperature of the sulfur incineration furnace Alternatively, a diesel gun can be used directly to raise the temperature of the sulfur combustion furnace and boilers; the flue gas must have a temperature higher than the dew point before it can be fed into the conversion system to facilitate further temperature increase. Otherwise, an electric heater must be used alone to heat up the conversion system. 3. The rest shall be started in accordance with the system startup procedure after a long-term shutdown of the system. 4. Special emphasis: Precautions and principles for using the system to inject sulfur dioxide into the furnace gas: 1) Gas supply principle: Low flow rate and low gas concentration ； 2) The sulfuric acid plant must assign a part-time analyst for exhaust gas analysis to continuously monitor the SO2 concentration in the exhaust gases in order to guide production operations; generally, the SO2 concentration in the exhaust gases is analyzed every few minutes or every 10 minutes to provide guidance. IV. Projects scheduled for maintenance: 1. Use cleaning machines to clean and unblock the clogged fire tubes, trying to avoid damaging the corundum protective sleeves ； After thorough cleaning, a boiler water pressure test must be conducted and it must pass. 2. Inspect the pipeline from the outlet of the drying tower to the inlet of the sulfur incinerator for blockages and clean it thoroughly ； 3. Clear the secondary air ducts in the middle and at the rear of the sulfur incineration furnace ； 4. Check that the sulfide gun, oil gun, oil pump, and sulfide pump are in good condition and ready for use. (The sulfide gun currently in use exhibits sulfide dripping and poor atomization.) 5. Improve the interlock mechanism between the main fan and the sulfide pump ； (The fan trips, so the sulfide pump must also trip; the sulfide pump trips, but the main fan does not trip.) ) Repair of leaks in the piping for system equipment weighing 60,000 and 80,000 tons. 7. Try to remove all the sediment at the bottom of the sulfonate pump tank ； 8. Whether to activate the second-stage catalyst bed of the converter is pending decision (1# heat pipe boiler has a pressure drop of only 68 mmH2O, so there is no major issue.) 9. Carefully organize the maintenance work as well as the start-up and shutdown procedures for the system. 2007-8-4