GB/T 35150.6-2024Technical requirements of dry process cement production complete equipment - Part 6: Desulphurization system (English PDF)

1 Scope

This document specifies the classification, composition, technical requirements, safety and environmental protection, installation acceptance and commissioning, performance testing and delivery documents of the desulphurization system of complete equipment for new dry process cement production.

This document applies to the design, manufacture, installation acceptance and performance testing of the desulphurization system within complete equipment for new dry process cement production.

3 Terms and definitions

3.1 wet desulphurization system: a system that achieves desulphurization by a process in which the absorbent enters the desulphurization system in solid form and the desulphurization by-product returns to the production system in a dry state.

3.2 compound desulphurization system: a system that achieves desulphurization by a process in which the absorbent enters the desulphurization system in a combination of solid and liquid form and the desulphurization by-product returns to the production system in a dry state.

3.3 dry desulphurization system: a system that achieves desulphurization by a process in which the absorbent enters in a dry state and reacts with SO2, the desulphurization by-product being in a dry state.

4 Classification and composition

4.1 Desulphurization systems are divided into wet desulphurization systems, compound desulphurization systems and dry desulphurization systems.

4.2.1 A wet desulphurization system consists of desulphurizing agent preparation equipment, desulphurization equipment, water supply equipment, by-product treatment equipment, slurry discharge and recovery equipment, and waste water treatment equipment.

4.2.2 A compound desulphurization system consists of a desulphurizing agent silo and a feeding device.

4.2.3 A dry desulphurization system consists of a desulphurizing agent silo and a conveying device.

5 Technical requirements

5.1.1 The wet desulphurization system shall comply with GB 51284 and HJ 179.

5.1.2 Equipment in the wet desulphurization system that comes into contact with slurry shall have a corrosion protection function.

5.1.3 Equipment in the compound desulphurization system that holds corrosive liquid shall have a corrosion protection function.

5.1.4 The dry desulphurization system shall comply with GB/T 19229.2.

5.1.5 Steel structures shall comply with GB 50205. Steel ladders, platforms and guardrails shall comply with GB 4053.1, GB 4053.2 and GB 4053.3. Welded parts shall comply with JC/T 532. Machine painting and rust prevention shall comply with JC/T 402. The packaging, transport and storage of the equipment and its parts shall comply with JC/T 406.

5.1.10 Centrifugal pumps used in the desulphurization system should be provided in two sets, one in service and the other on standby.

5.2.1 The performance requirements of the desulphurization system shall comply with Table 1. Table 1 sets, for each of the three types, the flue gas handling capacity in units of ten thousand cubic metres per hour, which runs from 10 to 150 for the wet single-tower, the compound and the dry system alike; the SO2 concentration before desulphurization, referred to the standard state, dry basis and 10 percent oxygen, which is not greater than 5 000 for the wet system, not greater than 2 000 for the compound system and not greater than 600 for the dry system; the SO2 concentration after desulphurization on the same basis, in milligrams per cubic metre, which is 0 to 35 for the wet and the compound systems and 5 to 100 for the dry system; the water consumption in tonnes per hour, 5 to 35 for the wet system and 0.4 to 2.5 for the compound system, water consumption not being a requirement for the dry system; the electricity consumption in kilowatt hours per tonne, 0.5 to 50 for the wet system and 0.05 to 0.1 for the compound and dry systems; and the calcium to sulfur molar ratio, 1.02 to 1.05 for the wet system and less than 10 for the dry system, this ratio not being a requirement for the compound system. A continuation row of Table 1 fixes the mass ratio between desulphurizing agent consumed and SO2 removed, separately for the solid agent and for the liquid agent; the OCR of that row does not allow each figure to be attached to its column with certainty, so the figures are not reproduced here. A note states that a dash marks an item that is not a requirement.

5.2.2 The desulphurization efficiency of the system shall satisfy what the contract provides.

5.3.1 Desulphurizing agent preparation equipment consists of a reclaiming device or silo, a slurry preparation tank and centrifugal pumps. Preparation shall comply with JB/T 14499, the silo with NB/T 47003.2 and the centrifugal pumps with GB/T 5656. The slurry preparation tank shall be fitted with an agitator complying with HG/T 20569.

5.3.2.1 The desulphurization equipment consists of the desulphurization tower, circulating pumps, oxidation air blowers, a sump and return equipment.

5.3.2.2 The desulphurization tower shall comply with JB/T 12537 and NB/T 47003.1.

5.3.2.3 Within 2 m of the inlet, the tower flue duct should be faced with stainless steel plate whose material properties shall not be lower than those of 022Cr23Ni5Mo3N (S22053) in GB/T 4237-2015.

5.3.2.4 The tower inlet flue duct shall be fitted with an emergency water spray cooling device. The tower outlet flue duct shall be fitted with a drainage device. The flue damper of the tower shall comply with JB/T 10992.

5.3.2.7 The mist eliminator of the tower shall comply with JB/T 10989, the spray pipes with JB/T 10991 and the nozzles with JB/T 10964. The tower should use a side-entry agitator complying with JB/T 10983, slurry circulating pumps should be slurry centrifugal pumps complying with JB/T 11834, oxidation air blowers should be Roots blowers complying with JB/T 8941.1, and the oxidation air ducts shall comply with JB/T 11264.

5.3.2.17 Slurry piping of the wet desulphurization system should be rubber-lined carbon steel, glass fibre reinforced plastic or duplex stainless steel; rubber-lined carbon steel piping shall comply with HG 21501, glass fibre reinforced plastic piping with HG/T 21633, and duplex stainless steel piping with GB/T 21833.2.

5.3.3.3 The capacity of the water supply tank shall be not less than one hour of system water consumption.

5.3.4.1 By-product treatment equipment consists of centrifugal pumps, hydrocyclones and a vacuum belt dewatering machine; the hydrocyclones shall comply with JB/T 10984 and the vacuum belt dewatering machine with JB/T 10982.

5.3.5.2 The desulphurization system shall be provided with one emergency slurry tank.

5.3.6.2 Desulphurization waste water treatment equipment shall comply with JB/T 11392; the settling tank and the water tank should be of steel construction.

5.4 The compound desulphurizing agent consists of a solid agent and a liquid agent. The solid agent silo should be a steel silo complying with NB/T 47003.2, with a bag filter complying with JB/T 11642 on top and a screw feeder complying with JB/T 11933 as the feeding device. The liquid agent silo should be an atmospheric vessel complying with NB/T 47003.1, fed by a centrifugal pump complying with GB/T 5656.

5.5 In the dry desulphurization system the agent silo should be a steel silo complying with NB/T 47003.2, with a bag filter complying with JB/T 11642 on top and a screw feeder complying with JB/T 11933 as the conveying device. Equipment insulation shall comply with GB 50264.

5.6.4 The energy efficiency class of the motors shall meet class 2 of Table 1 of GB 18613-2020.

5.6.8 The desulphurization system shall use a distributed control system, whose network security shall comply with GB/T 33009.1.

5.6.9 The control parameters of the wet system shall include the inlet and outlet temperature, the level, the pH and the mist eliminator differential pressure of the tower, the level and density of the slurry preparation tank, and the levels of the sump, the water supply equipment, the by-product treatment equipment and the waste water treatment equipment.

5.6.10 The control parameters of the compound system shall include the level in the powder agent silo, the level of the desulphurization liquid, the flow of the powder agent, the flow of the liquid agent, and the compressed air pressure used to atomise the liquid agent.

5.6.11 The control parameters of the dry system shall include at least the level in the powder agent silo and the flow of the powder agent.

6 Safety and environmental protection

6.1.1 The mechanical and electrical safety of the desulphurization system shall comply with GB/T 5226.1.

6.1.2 The system shall be provided with measures against unexpected start-up complying with GB/T 19670.

6.1.3 Exposed rotating parts of transmission devices shall be fitted with guards or guard nets complying with GB/T 8196.

6.1.4 Safety warning signs complying with GB 2894 shall be provided; interlocking devices shall comply with GB/T 18831 and emergency stop devices with GB/T 16754.

6.1.7 Where the surface temperature of equipment and piping exceeds 50 degrees Celsius, protective measures shall be taken at positions people can easily touch.

6.1.8 Alarm devices for slurry level and density shall be provided.

6.1.9 The selection, installation and alarm signal of the ammonia leak detector of the compound system shall comply with GB/T 50493.

6.2.1 Noise control at working positions shall comply with GB/T 50087; waste gas emission shall comply with GB 4915; and waste water shall be recycled after treatment.

7 Installation acceptance and commissioning

7.1.1 Construction and acceptance of the installation work shall comply with JCJ/T 3.

7.1.2 Installation acceptance and a performance test shall be carried out before delivery. Before the plant goes into production, single-machine trial running, no-load linkage trial running and load trial running shall be carried out, and a performance assessment test shall follow the end of commissioning.

7.2.1 Before commissioning the following preparations shall be made: documentation, including equipment instruction manuals and installation acceptance reports; commissioning personnel, meaning process, equipment and electrical specialists together with production operators; identification of hazards on site according to the characteristics of the equipment, with emergency plans drawn up; and a commissioning plan covering the purpose, the schedule, the organisation and coordination of personnel, training, raw material preparation, single-machine trial running, no-load linkage trial running, load trial running and spare parts.

7.2.2 The no-load running test of each machine shall comply with the relevant machine standard. Single-machine trial running shall confirm that lubrication systems, control systems and temperature and pressure detection equipment work normally, and adjustment shall follow where they do not. It should include checking the direction of motor rotation, the opening and closing of valves, the correctness of instrument signals, and the pressure and flow of the water and air supplies.

7.2.3 No-load linkage trial running shall follow the single-machine trials and should check whether the grouping of equipment meets process requirements, whether the group start and stop sequences and the intervals between starting and stopping are satisfactory, whether the process interlock conditions are reasonable, whether the safety interlocks meet process requirements, and whether the process parameters such as temperature, air volume and air pressure meet the conditions for load trial running.

7.2.4 Load trial running is carried out only once all equipment has passed no-load running, the power supply and distribution and its interlock and control systems work normally, and the raw materials in store meet the needs of the trial. It follows the principles of safety first, quality first and step-by-step progress; the load scheme is set from the size and design of the system, and the load is raised gradually to 100 percent and held stable. Acceptance trial running shall satisfy the performance requirements of 5.2.

8 Performance testing

8.1 The test instruments and their accuracy shall meet the requirements of the relevant test standards.

8.2 The scope of the performance assessment is the complete desulphurization system; where there are special requirements the scope is to be defined again.

8.3.1 Instruments used for temperature, pressure, dust concentration and similar measurements shall meet the accuracy required by GB/T 26282. Measuring equipment shall be verified and calibrated, and the record kept. Assessment personnel from each discipline shall be in place and the recording forms prepared for the test content.

8.4 The test parameters shall comply with Table 1; the test method for the desulphurization system shall comply with GB/T 21508; and the electrical energy efficiency test shall comply with GB/T 27977.

8.5.1 Table 2 sets out, item by item, what is tested, by which method and how often over 24 hours, and which of the three system types the item applies to. Flue gas handling capacity is tested to GB/T 21508 three times; the SO2 concentration before desulphurization is measured continuously to GB 4915 and the concentration after desulphurization continuously to GB 4915, HJ 75 and HJ 76; water consumption, electricity consumption and the calcium to sulfur ratio are measured continuously to GB/T 21508; the mass ratio of desulphurizing agent to SO2 removed is measured continuously by the procedure of 8.5.3; the moisture content of the gypsum is tested to GB/T 5484 three times; and noise is tested to GB/T 17248.3 three times.

8.5.2 The desulphurization efficiency is the percentage that the quantity of SO2 removed by the system bears to the quantity of SO2 contained in the flue gas before desulphurization, and is calculated by formula (1). In the formula, the efficiency is expressed as a percentage; C1 is the SO2 concentration in the flue gas before desulphurization at 101 325 Pa and 0 degrees Celsius, dry basis, in milligrams per cubic metre; Q1 is the total flue gas discharged over 10 continuous minutes before desulphurization on the same basis, in cubic metres; C2 is the SO2 concentration in the flue gas after desulphurization on the same basis; and Q2 is the total flue gas discharged over 10 continuous minutes after desulphurization.

8.5.3 For the mass ratio of compound desulphurizing agent to SO2 removed, with the raw mill stopped and all desulphurizing agent taken out of service for 10 minutes, the converted SO2 concentration C1 in the kiln tail stack, taken as the average of 10 continuous minutes of data, and the total stack gas discharged Q1 are measured; from 10 minutes after the agent is put back into service, the converted SO2 concentration C2, again averaged over 10 continuous minutes, and the total stack gas discharged Q2 are measured; the mass of solid agent consumed is m1 and the mass of liquid agent consumed is m2. Formulas (2) and (3) give the solid and liquid mass ratios respectively, with the masses in milligrams, the concentrations in milligrams per cubic metre and the gas volumes in cubic metres.

8.6 The data are processed for each 24 hours; the deviation between the three sets of 24-hour data shall be less than 5 percent, failing which the result is invalid and the test is to be repeated, and the reported result is the average of the measurements.

8.7 Table 3 lists the items that go into the test report and which of them apply to each system type: flue gas handling capacity, the SO2 concentrations before and after desulphurization, water consumption, electricity consumption, the calcium to sulfur ratio, the desulphurization efficiency, the mass ratio of desulphurizing agent to SO2 removed, the moisture content of the gypsum, and noise.

9 Delivery documents

9.1 The instruction manuals for the various pieces of equipment in the desulphurization system shall comply with GB/T 9969.

9.2 Within the period fixed by the contract and in accordance with its requirements, the installation instructions and installation drawings, the product instruction manual, the commissioning instructions and the instructions for the electrical control system shall be supplied, so that the system equipment is correctly installed, properly used and operated to advantage.