Soda Ash Calcining and Cooling System Project Proposal Shandong Tianli R&D Institute July, 2008 1
1. General 1.1 Company Introduction Tianli R&D Institute is a comprehensive technology company which belongs to Shandong Academy of Science and relies on many universities, scientific research institutes, such as Shandong University, Tianchen Design Institute, Shandong Light Industry Design Institute, Shandong Chemical Plan & Design Institute and etc. It specializes in research, development, sales, design, manufacture and installation of fuel ethanol, plant essence extraction, new type building material, drying and calcining, and personnel training and consulting service. 1.2 The Brief Introduction of Project Project name: Soda Ash Calcining and Cooling Project Contracting unit: Tianli R&D Institute Project scale: 1)100000 t/a, 150000 t/a, 200000 t/a, 400000 t/a soda ash dense calcining/cooling system. 2)100000 t/a, 150000 t/a, 200000 t/a soda ash light calcining/cooling system. The project is a part of the large-scaled soda ash calcining/cooling production line, aiming to make natrium carbonicum calcinatum from wet soda ash dense/light separated from vacuum filter. First, the free water is removed; the next step is to decompose ammonium acid carbonate and sodium bicarbonate, at last, the required ash soda will be obtained. The core technology is of a fluidized-bed calcining/cooling system with an in-bed heat exchanger. Calcining and cooling can take place in the same equipment, which reduce process flow and equipment investment greatly. In addition, we can offer soda ash dense production technology concerning liquid phase hydration method. 1.3 Industry and Market Environment Soda ash (sodium carbonate), one of the most important chemical materials, is applied in chemicals production, cleaning agent production, detergent production, 2
photography and pharmacy. A majority of soda ash is widely used in industrial filed, including two third of it being used in light industry, building material industry and chemical industry, and one third being used in metallurgy industry, textile industry, petroleum industry, national defense, medicine and other industries. Sine production of per ton glass will consume 0.2 tons of soda ash, the glass industry becomes the largest consumer for soda ash. Soda ash is applied to produce waterglass, sodium dichromate, sodium nitrate, sodium fluoride, sodium bicarbonate, borax, and etc. for chemical industry. It can be also used as the smelting agent in metallurgy industry, as the suspending agent for mine rock selection, the desulfurizer for steelmaking and antimony making, osmosis agent in printing and dyeing industry. It is also used to degrease the leathern, counteract chrome leather and improve the alkalinity of chrome tanning liquor in leather industry, and produce synthetic detergent additives such as sodium tripolyphosphate and other sodium phosphate. Thanks to the steady development of glass industry, the consumption of soda ash is rising rapidly. The global consumption in soda ash market will be annually increased by 4% in the next four years and the global demand will reach 47,000,000 tons by the year of 2012. The major manufacturing regions are China, Middle East and East Europe. The consumption of soda ash in China increase strongly, and the supply shortage conducted by expansion shortage, which all lead to the tension of the global market. 1.4 Prospect The project is expected to have a broad developing space, because the demand for soda ash is growing rapidly in the world. The technology of fluidized-bed with in-bed heating exchanger developed by our institute has earned most domestic market shares of synthesis alkali, therefore, this project is of a promising prospect. 2. Market Analysis The project is mainly applied in soda ash production industry, therefore, our orientation in market is large-scaled soda ash production enterprises. The world production areas of soda ash mainly covers China, North America and Europe, which amounts to more than 85% of the total world production volume.. 3
China s soda ash output will be 17,200,000 tons by the end of 2006, amounting to 34% of the total world output and taking the first place in the world with share of Europe being 29% and North America being 23%. At present, some countries and regions such as North America, West Europe, Japan, Korea, and Taiwan are in the stable period of soda ash consumption, however, China, India and East Europe are developing at a high speed and construction and automobile industries in these countries are growing at an unparalleling speed in history, making a huge demand for soda ash and promoting the rapid growth in production capacity. Hence, the future world growth in soda ash production will concentrate in China, India and Eastern Europe.. Thanks to the steady development of glass industry, the consumption of soda ash is rising rapidly. The global consumption in soda ash market will be annually increased by 4% in the next four years and the global demand will reach 47,000,000 tons by the year of 2012. The major manufacturing regions are China, Middle East and East Europe. Because the supply and demand is relatively stable in North America and Western Europe, it is not likely for them to increase their production of soda ash in future years. But in Eastern Europe and Mid-east where supply and demand is relatively unbalanced, there will be a few production lines to put into operation in 2008, which will ease the tension between the supply and demand. There will be 1,000,000 tons of growth in soada ash production in Eastern Europe in future years, so there will be a certain market in Eastern Europe and Mid-east regions, however, the market potential is not large. 2.1 Technical Advantages The conventional calcining process of soda ash dense production has many disadvantages such as expensive investment, large site area, costly operation and maintenance fees, long process flow with many units of equipment. Moreover, the separated fine powders can not return to the hydration process, resulting in high investment of civil construction. Besides, the past practice also has the following 4
weaknesses in low production capacity, short service period, high energy consumption, serious environmental pollution, heavy dust collecting machine, lower lye recovery rate and the exhaust with lye impacting the service life of fans, and etc. The new type fluidized bed calcinatory/cooler with in-bed heat exchanger which is explored and developed by our institute, however, has many advantages, such as high thermal efficiency, easy operation, less investment. The drying and cooling of soda ash dense can be completed in one system, which also has the function of an air classifier for soda ash dense. The technical innovation makes up the above mentioned disadvantages of the past practice and is the patent of our institute. Among the similar series of products, our product has arrived at the international leading level and successfully applied in many domestic famous soda ash production enterprises with good economic and environmental protection effects. Taking 200,000 ton/a soda ash dense as example, economic and technical analysis of three technologies is compared as the following table: The comparison of three technologies Steam rotary Single-stage Multistage calcinator ebullience fluidized ebullience fluidized calcining calcination cooling calcination cooling technology technology technology Technology Complex flow Simple flow Simple flow Equipment in Equipment in less Equipment in small large quantity quantity quantity Equipments (yuan) investment 10,000,000 8,000,000 5,500,000 Floor area large larger small Running attention complex simple simple Steam consumption ton/h 0.45 0.5 0.45 Power kwh/ton consumption 16.2 25.6 20.8 5
The equipment is of a lot of innovation in some respects such as in process flow, main equipment fabricaition, equipment layout and automatic control compared with introduced technologies, some technologies are firstly used in the domestic and foreign industry. Its advantages in technology are as follows: 1) Compared with the equipment in the same industry, the bed area is reduced greatly, so the air consumption for drying and cooling units is reduced accordingly. Because of the simple structure of fluidized bed and small heat exchange area one fourth less than that of the rotary kiln with the same size, the investment of equipment is lowered down greatly. 2) The pre-mixer located on the fluidized bed, on the one hand, can be used to avoid duct adhesion and shaping lye balls for purpose of a long and smooth performance, on the other hand, it helps reduce the height of hydrator in terms of arrangement because monohydrate may enter the bed from the side. 3) The soft water can be saved greatly by using standard well water as the neutralized water instead of by using dedusted lye, which often results in monohydrated being discharged due to its color turning into red. 4) The employment of lye-return method causes the feeding water level lowered down, avoiding adhesion of material and ensuring a long smooth performance of system with less maintenance fee. 5) Since fluidization area is small, the required air consumption for fluidization is reduced greatly, some unnecessary units such as lye pump can be removed from the process, making the motor power consumption for drying fan, cooling fan and draught fan reduced greatly. 6) Compared with this same type of fluidized bed, the operation bed in this plant is higher and the outlet temperature is much lower in calcining area, while the outlet temperature at cooling point is greatly increased and the outlet temperature of mixed gas is still far higher than the dew point, which ensures the normal performance of bag dust-collector. Due to the less hot air in the fluidized bed, low outlet temperature in calcining area and long time of high load operation, the steam consumption is greatly reduced with a perfect effect of energy conservation. 6
7) The whole process is controlled by advanced high automation PLC control system and the labor intensity of workers is reduced. 8) The simple structure of fluidized bed, simplified process, less equipment, concise piping make the investment of equipments, piping, valves, electrical apparatus, instruments, civil construction and installation reduced at different degrees. At the same time, the service life of equipment is extended with the stable operation. 2.2 Marketing Advantages The fluidized calcining equipment for soda ash developed by our company have some advantages such as small site area, operating flexibility, and less one-time investment.. So it is competitive in market and has earned most domestic shares of synthesis alkali.. Therefore, our products are popular in international market with more competitive price. 3. Process Flow 3.1 Process flow description 3.1.1 Process flow diagram for soda ash dense a. go to condensate pipeline network; b. 1.8MPa steam from pipeline network; c. raw material from hydration machine; d. go to hydration machine; e. emptying f. cooling backwater going to backwater system; g. finished soda ash dense; h. cooling inlet water from circulation for soda ash dense; 1. air filter; 2. blower 7
3. heat exchanger; 4. out rotary valve; 5. rotary valve for accumulation of salt in the surface soil 6. fluidized bed for soda ash dense; 7. spider feeder; 8. pre-mixing device; 9. rotary valve; 10. cyclone separator; 11. bag-type dust collector 12. exhauster 3.1.2 Process flow diagram for soda ash light a. compressed air from pipeline network; b. burner gas to compressor; c. crude soda ash dense; d. 3.2MPa steam from pip network; e. go to condensate pipeline network; f. compressed air from pipeline network; 1. burner gas bag-type dust collector; 2. burner gas cyclone separator; 3. spider govern for accumulation of salt in the surface soil; 4. screw for soda ash dense; 5. belt for soda ash dense; 6. bucket elevator; 7. pre-mixing machine with spider sealing for soda ash dense; 8. pre-mixing machine; 9. fluidized calcining equipment; 10. conveying skew scraper; 11. out-feed screw; 12. out-feed spider govern; 13. centrifugal fan; 14. circulatory cyclone separator; 15. circulatory bag-type dust collector; 16. circulatory bag-type machine with under spider sealing; 3.2 Technical Strengths 3.2.1 Technical characteristics of soda ash dense in calcining/cooling system 8
Drying and cooling of dense soda ash are completed in one system. A special design for drying/cooling of soda ash has been proposed. The hot and cold air for soda ash drying/cooling is supplied by both in-bed heat exchanger and a cooling air system. Additionally, the cooling system has the function of an air classifier for dense soda ash. (1) Short flow fluidization principle is used to make calcining and cooling of dense soda ash: a. Fluidization ensures thickness and residence time of fluidized material bed and can realize the adjustment within the desired range, so calcination quality of the material can be guaranteed. b. Since there is fluidized air, fluidization/calcination reduces material stickiness during internal heating, material can be processed under stable conditions with low material return. c. Main equipment for fluidization/calcination is static, only a blower and some feeding devices in the whole technology are dynamic systems, so quality inspection cost of equipment is reduced greatly and its cost is decreased. d. Short flow design decreases energy consumption, reduces the occupied area and saves investment costs. (2) A multi-layer in-bed heat exchanger structure is used. The device uses two-layer in-bed heat exchanger structure, height of single-layer in-bed heat exchanger reaches 2.5 m, height of whole fluidization part reaches about 5.0 mm. Application of the structure has the following advantages: a. Since multi-layer in-bed heat exchanger structure is used, more heat exchangers can be arranged on a small area vertically, fluidization area of the system is reduced greatly, so the fluidization area of the equipment for light soda ash fluidization/calcination with annual output of 200,000 ton is only 1/3 of imported equipment. b. Since fluidization area of the equipment is small, the required air for fluidization is reduced greatly, the volume of the downstream cyclone, bag filter and air pipe is 9
small to the overall volume of the equipment and the overall investment of equipment is low. c. Since the overall volume of the equipment is small, the investment of factory building and civil engineering is low. (3) Pre-mixing feeding device is used: a. To prevent from fouling of heat exchanger, agglomerating of soda ash in the bed and to ensure long-term operation. b. Monohydrate enters the bed from the side of the fluidized bed and installing height of the hydration device is lowered. 3.2.2 Technical charateristics of soda ash dense in calcining/cooling system A special design for calcination of light soda ash is offered. Heat required for soda ash calcination is supplied by both in-bed heat exchanger and air system. The equipment has high thermal efficiency and occupies small area. It suits the expansion of soda ash factories. (1) Fluidization principle is used to make calcination of soda ash light: a. Fluidization/calcination ensures thickness and residence time of fluidized material bed and can realize the adjustment within the desired range, so calcination quality of the material can be guaranteed. b. Since there is fluidized air, fluidization/calcination reduces material stickiness during internal heating, material can be processed under stable conditions with low material return. c. Operation flexibility of fluidization/calcination is large; the equipment operation is stable. d. Main equipment for fluidization/calcination is static, only a blower and some feeding devices in the whole technology are dynamic systems, so quality inspection cost of equipment is reduced greatly and its cost is decreased. (2) A multi-layer in-bed heat exchanger structure is used. The device uses a two-layer in-bed heat exchanger structure. Application of this structure has the following advantages: 10
a. Since multi-layer in-bed heat exchanger structure is used, more heat exchangers can be arranged on a small area vertically, fluidization area of the system is reduced greatly, so the fluidization area of the equipment for light soda ash fluidization/calcination with annual output of 100,000 ton is only 12 m2, and that with annual output of 200,000 ton is only 16 m2. b. Since fluidization area of the equipment is small, the required air for fluidization is reduced greatly, the volume of the downstream cyclone, bag filter and air pipe is small to the overall volume of the equipment and the overall investment of equipment is low. c. Since the overall volume of the equipment is small, the investment of factory building and civil engineering is low. (3) A closed-circulation system is used: a. Since a closed-circulation system is used and there is no fresh air for supplementation, it ensured the CO2 concentration no less than 92% and convenient for CO2 recovery. b. High-temperature CO2 is used as a fluidizing gas and additional heating source is not required. This can save energy consumption. The consumption of steam per ton of final soda ash is below 1.2 ton. Steam consumption for soda ash light is reduced and energy is saved. c. CO2 generated by the calcination is discharged outside circulation and recovered by a lye recovery device, so the energy is fully utilized. d. Through flash vaporizer, the condensed water from in-bed heat exchanger becomes low pressure steam which is used for heating other medium, therefore the energy utilization is high. 3.3 Main Equipment Introduction The front part of the fluidized-bed machine is of the drying system used for removing the surface water in particles of soda ash. After properly calculation, the hot airflow will via air distribution plate pass through the soda ash in machine, keeping the particles suspending in the airflow and forming it to be fluidized shape. Fluidized 11
soda ash particles are uniformly mixed in bed and thoroughly contacted with the airflow, conducting intense heat & mass transfer and carrying out perfect removal of surface water and internal water. In the calcining system there are some heat exchangers, where the hot steam flows and its heat will be transfer to the soda ash via tube wall and calcine the soda ash. At the end part of the equipment, soda ash particles are cooled by the heat exchanger within cooling water. Fluidized design is suitable for conveying soda ash particles. During the process of drying, the material can avoid partially over heated. Therefore, this design is preferred for heat sensitive product. A relatively high thermal efficiency can be achieved because the outcoming gas temperature is lower than the highest temperature of product. The cannular heat-exchangers are equipped in the fluidized bed for indirect heating and calcining. By using them a high speed of evaporation can be achieved at a lower temperature. Bu using this type of machine the soda ash is first removed its surface water and then calcined by means of in-bed heat exchanger with less investment and operating cost. 3.4 Environmental Protection and Energy Saving 3.4.1 Environment protection criteria In order to beautify the environment, greening is taken into account in this project. Shrubs, lawns and some pine trees or bamboos will be planted. Tall arbor trees will stand on both sides of road, helping protecting from dust, noise and emission of harmful gas. In addition, we make good use of the designated lands by planting more greening zones for cleaning the air and improving environment. The sound pressure levels of equipment to be purchased are in accordance to the related requirements. If their noise level will exceed the limits allowed by the regulation, they shall be equipped with silencer or acoustic enclosure. Noise levels: NO Parameter Specification 1 Leq, 8 hours 85 db (A) 2 4 hours 88 db (A) 12
3 1 hour 94 db (A) 3.4.2 energy-saving measures The main power supply for production of soda ash comes from the electricity generation and coal fired boiler. We can take the following energy-saving measures against excessive energy consumption in the process of production. (1) power-saving measures It is implemented by advanced technology, appropriate equipped capacitor, inactivity automatic filter, in addition, we can improve the quality of voltage in electric network, reduce the consumption of transmission and distribution system and transformer, and strengthen some necessary management and operating rules. (2) Pyretogenic energy-saving measures The consumption of the heat source is steam, which mainly lies on the consumption of normal operation and the loss resulted from wear and tear of pipelines; it is implemented by adopting condensing recovery system so as to recollect all the condensing steam generated in the production plant and others used steam by the recovery equipment to reuse. In addition, in order to control the consumption of the steam, we will do the insulation work for all the equipments and pipelines to reduce the loss of the heat energy and as well as install the necessary steam-measuring facility at the same time. 4. Conclusion The new type fluidized bed calcinatory/cooler with in-bed heat exchanger, which is designed and developed by our institute, excels in its low investment and energy consumption. Its high thermal efficiency and less operation and maintenance fees make this project profitable in terms of finance and turn period. 13