Thread Content
【Renovation of the sulfuric acid waste heat system generates 3.1 million yuan in benefits for the enterprise】: The Tianjin Sulfuric Acid Factory invested 1.5 million yuan to upgrade its waste heat system, and within just one year of operation, this system generated over 3.1 million yuan in benefits for the enterprise. The plant features a two-turn two-suction process for producing 120,000 tons of sulfuric acid per year; the heat generated by burning sulfur is used to produce 9.6 tons of superheated steam per hour via medium-pressure waste heat boilers. In the past, part of this superheated steam was used for chemical production after being cooled and depressurized, while another part was used in extraction-condensing steam turbine generators, with the electricity generated fed into the North China power grid. Due to the complex system operation and cumbersome grid connection process, the utilization rate of waste heat recovery devices is very low. To change this situation, the plant adopted a renovation scheme in which centrifugal blowers of the DG800-12 type produced by Shenyang Blower Factory were driven directly by steam turbines, thereby ensuring the reliability and stability of the waste heat utilization system. Currently, in the sulfuric acid production process at this plant, 70% of the medium-pressure steam generated by the medium-pressure waste heat boiler located at the outlet of the sulfur incinerator is used to drive the main blower via a turbine; the remaining steam is cooled and depressurized before being used for insulating the sulfur storage tanks and associated pipelines, as well as being sent to the low-pressure steam network. The 4 tons per hour of low-pressure steam produced by the low-pressure boiler at the outlet of the fourth conversion stage is entirely fed into the low-pressure steam network for use in chemical manufacturing and winter heating. In this way, apart from the heating required to start up the system, all the waste heat can be utilized to generate steam for industrial processes, thereby eliminating the need to operate coal-fired boilers. Source: China Chemical Industry News, Han Yulin. 【Toxicity of sulfuric acid and first aid measures for poisoning】: Name: Sulfuric acid; sulfuric acid solution; lead chamber acid; battery sulfuric acid; sulfur trioxide; sulfuric anhydride. Physical and chemical properties: Pure sulfuric acid is a transparent, colorless, odorless oily liquid; the presence of impurities causes it to darken in color, or even turn black. Molecular formula: H2SO4. Molecular weight: 98.08. Its relative density and freezing point also vary depending on its content. Relative density 1.841 (96–98%). Freezing points: 10.35°C (100%), 3°C (98%), -32°C (93%), -38°C (78%), -44°C (74%), -64°C (65%). Boiling point 290°C. Vapor pressure 0.13 kPa (145.8°C). It has a strong affinity for water. Absorbs moisture from air and organic matter. When mixed with water or alcohols, it generates a large amount of heat and its volume decreases. When diluting with water, add the acid to the diluted water to prevent the acid from splashing during boiling. When heated to 340°C, it decomposes into sulfur trioxide and water. Dilute acids can react with many metals to release hydrogen gas. Concentrated acid does not corrode lead or low-carbon steel; it is a very strong acidic oxidant. It can burn or even explode upon contact with many substances, and can react with oxidizers or reducers. Sulfur trioxide has three allotropes: α, β, and γ. The most useful form for commercial purposes is the γ variant, which appears as ice-like crystalline masses or a liquid. Molecular formula SO3. Molecular weight 80.07. Relative density 1.9224 (20°C). Melting point 16.8°C. Boiling point 44.8°C. Vapor pressure 57.72 kPa (25°C). Its solubility in water is 100%. It dissolves in water to form sulfuric acid; when dissolved in concentrated sulfuric acid, it forms fuming sulfuric acid while releasing a large amount of heat. Anhydrous sulfur trioxide does not corrode metals. Fire-fighting measures involve using water, dry powder, or carbon dioxide to extinguish the fire. Avoid spraying water directly onto sulfuric acid, as it can release a large amount of heat upon contact with water and cause skin burns. Firefighters must wear full protective gear and its accessories to prevent burns. Shipping and handling notes: Packaging label: Corrosive substance. Packaging method: Class (II). Transported in wooden crates outside glass bottles, or in wooden lattice boxes or iron tank cars outside acid jars. Storage and transportation conditions: Sulfuric acid should be stored separately in a well-ventilated, cool, and dry place, on an acid-resistant floor. Avoid direct sunlight. Keep away from sources of fire. The storage tank should have sufficient ventilation holes and be surrounded by a \"dam\" to prevent leaks. Storage and transportation in combination with chromates, chlorates, calcium carbide, fluorides, perchlorates, fulminates, nitrates, picrates, metal powders, and flammable materials are strictly prohibited. Staff must wear acid-resistant work clothes, rubber aprons, long boots, gloves, as well as protective glasses and masks. Fire hydrants and water pipes should be installed near the warehouse. Do not pour water directly into sulfuric acid during shipping to prevent an explosive reaction of the acid. For dealing with leaks, it is necessary to wear a gas mask and gloves. Sodium carbonate should be spread on the contaminated ground, followed by rinsing with water; the diluted wastewater should then be discharged into the waste water system. Opportunities for contact: sulfuric acid and chlorosulfonic acid industries; sulfonation of organic compounds; **manufacturing; production of fertilizers, dyes, adhesives, and rayon; electroplating, etching; laboratory reagents, food additives. It can be rapidly absorbed through the respiratory tract, digestive tract, and skin. Toxicology overview: Oral LD50 in rats: 2140 mg/kg ； Inhalation LC50: 510 mg/m3/2H. Mouse inhalation LC50: 320 mg/m3/2H. Liquid sulfuric acid is irritating and corrosive to the skin and mucous membranes. The irritant effect of fog on mucous membranes is stronger than that of sulfur dioxide; it primarily causes tissue dehydration and protein coagulation, which can lead to local necrosis. The site of toxicity to the respiratory tract varies depending on the inhalation concentration and droplet size. The human olfactory threshold is 1 mg/m^3. A concentration of 2 mg/m^3 can cause irritation in the nose and throat, while 6–8 mg/m^3 induces severe coughing. Ingesting 1 ml of concentrated sulfuric acid can be fatal. Sulfur trioxide is readily soluble in water to form sulfuric acid, and its toxic effects are the same as those of sulfuric acid. The 6-hour inhalation MLC for deer mice is 30 mg/m^3. Toxicity of sulfuric acid and first aid measures for poisoning: Clinical manifestations – Acute inhalation poisoning: Inhaling acid mist can cause significant irritation of the upper respiratory tract as well as bronchitis; in severe cases, chemical pneumonia or pulmonary edema may develop rapidly. At high concentrations, it can cause laryngeal spasm and edema, leading to suffocation. Associated with conjunctivitis and pharyngitis. Acute oral poisoning: It can cause burns to the digestive tract. Severe burning pain in the mouth, pharynx, retrosternal area, and abdomen appears immediately, along with erosion and ulcers of the lips, mouth, and pharynx, hoarseness, difficulty swallowing, vomiting of blood, and the presence of fragments of esophageal and gastric mucosa in the vomit; bloody stools may also occur. In severe cases, laryngeal edema or gastrointestinal perforation, as well as kidney damage, can occur. Skin burns: Local stinging occurs when the skin comes into contact with concentrated sulfuric acid; if no treatment is given, the area may change from redness to dark brown, and ulcers can develop – these ulcers have clear boundaries, are slightly swollen around the edges, and cause severe pain. Eye burns: Foreign objects entering the eye can cause conjunctivitis, conjunctival edema, corneal ulcers, and even perforation. Those exposed to inhaled sulfuric acid mist should be immediately removed from the scene to a place with fresh air, kept quiet, and kept warm. In the event of eye or skin contact with the liquid, first absorb it with a soft, clean cloth, and then rinse thoroughly with water immediately. In cases where those who took it orally have developed symptoms of gastrointestinal corrosion, induced vomiting and gastric lavage should be avoided. Those who develop symptoms after inhalation are treated symptomatically. Those who have inhaled a large amount should rest in bed, receive oxygen therapy, and be given nebulized inhalations of bronchodilator mist or dexamethasone. Patients with acute poisoning require appropriate oxygen therapy; glucocorticoids should be used early, in appropriate doses, for a short period of time; airway patency must be maintained; and laryngeal edema or spasm must be prevented.