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300-1000MW SCR denitration unit

key word:Heat exchange element


Product description

300-1000mw SCR denitration unit

 

1. Introduction

1.1. Purpose

Denitration device is one of the main environmental protection equipment in thermal power plant, which is used to reduce the emission of nitrogen oxides in flue gas.

1.2. Model meaning

                                 ** - 1900 / 25.4 – YW 1 - SCR

                                 **-----------Code of denitration equipment engineering company (Pinyin)

                                1900 ------ maximum continuous evaporation capacity of carrier boiler in denitration unit (T / h)

                                25.4 --------outlet pressure of main steam of carrier boiler of denitration unit (MPA)

                                YM -------- fuel type of carrier boiler in denitration unit (YM bituminous coal; PM lean coal; HM lignite; y-oil; q-gas)

                                1------------No. of carrier furnace type of denitration unit (furnace type number of this capacity grade is Arabic numerals, such as 1,2...)

                                SCR-------Code of selective catalytic reduction denitration device

1.3. Structural features

1.3.1. General layout (applicable to 300-100mw SCR). Selective catalytic reduction (SCR) denitration technology is adopted in the denitration unit. Each unit is equipped with two or one denitration reactors, which are arranged in the space behind the economizer and in front of the air preheater (behind the boiler tail column). The catalyst of denitration unit is arranged as 2 + 1 or 1 + 2, that is, 2 layers of operation, 1 layer of standby or 1 layer of operation and 2 layers of standby; the form of catalyst is honeycomb or plate type. The inlet of denitrification device is arranged in vertical flue, and ammonia spraying grid is generally arranged in vertical flue.

Denitration unit is divided into ammonia area and reactor area.

The ammonia area is mainly composed of discharge compressor, ammonia storage tank, liquid ammonia evaporation tank, ammonia buffer tank, ammonia dilution tank, waste water pump, ammonia pump (optional), waste water tank, instrument gas tank (if necessary), etc. This system provides ammonia for denitration reaction. Liquid ammonia is transported by liquid ammonia tank car. Liquid ammonia is transported into ammonia storage tank by liquid ammonia unloading compressor. Then, liquid ammonia in ammonia storage tank is transported to liquid ammonia evaporation tank by gravity and pressure difference of liquid ammonia or liquid ammonia pump to evaporate into ammonia gas. Certain pressure and flow are controlled by ammonia buffer tank, and then sent to ammonia / air mixer in reactor area, and then sprayed into ammonia spray grid for reaction The device. The ammonia gas discharged from the ammonia system is discharged into the ammonia dilution tank, absorbed by water, discharged into the waste water pool, and then sent to the wastewater treatment plant for treatment through the waste water pump.

The reactor area mainly includes denitration steel structure platform and escalator, ammonia / air mixer, dilution fan, ammonia spray grid, SCR reactor, reactor inlet flue, reactor outlet flue, reactor bypass flue (optional), high temperature bypass flue of economizer

(optional) etc. The internal layout of SCR reactor includes guide plate, rectifier grid, catalyst, catalyst support beam, reinforcing rib and lifting rod

Guide rail, soot blower and other devices; guide device is set around the reactor shell, which can expand freely in hot state.

1.3.2. The process flow of typical denitration system with reactor bypass flue and economizer bypass flue is shown in Figure 1-1.

1.3.3. The process flow of typical denitration system without reactor bypass flue and economizer bypass flue is shown in Figure 1-2

1.3.4. Structural features of main components:

1.3.4.1. Catalyst. The catalysts used in flue gas denitrification of coal-fired boiler mainly include honeycomb catalyst and plate catalyst.

1.3.4.2. A group of ammonia spraying grids are arranged at the inlet flue of each reactor. The ammonia spraying grid is composed of pipe and nozzle, and nozzles are evenly arranged on the pipe to ensure uniform ammonia injection. The number of pipes and nozzles shall be determined according to the design conditions of each project.

1.3.4.3. Soot blowing system. In order to ensure the denitrification effect of catalyst, soot blowers are arranged above each layer of catalyst (only the position and space of soot blower are reserved above the reserved layer catalyst, but not installed). There are two main types of denitration soot blowers: acoustic soot blower and harrow steam soot blower. At present, acoustic soot blower is widely used in China.

1.3.4.4. Denitration reactor. The denitration reactor is the main body of denitration device, which is equipped with guide plate, rectifier grid, catalyst, catalyst support beam, reinforcing rib, lifting guide rail, soot blower and other devices. In addition, sealing devices are arranged between catalyst modules and between catalyst modules and reactor shell, which can prevent short circuit of flue gas and improve denitration efficiency.

1.3.4.5. Ammonia and air mixed supply device. The ammonia and air mixing supply device is a device which dilutes and mixes the ammonia gas regulated by the regulating valve with the air at the outlet of the dilution fan, and injects the mixture of ammonia and air into the ammonia spraying grid. The device is composed of ammonia / air mixer, dilution fan, pipeline, valve and various monitoring instruments. The main purpose of diluting ammonia with air is to dilute ammonia below the explosion limit (when the volume concentration of ammonia in the air is 15% ~ 28%, there is explosion risk, so the concentration of ammonia must be diluted below the lower limit of explosion limit).

1.4. Product series

1.4.1. According to the capacity level, it is divided into 300, 600 and 1000 MW series products.

1.4.2. According to the catalyst, it can be divided into honeycomb denitration and plate denitration series products.

1.4.3. According to the shape, it can be divided into air preheater pull-out type and air preheater non pulling type series products.

1.4.4. According to the type of reducing agent, it can be divided into liquid ammonia, urea and ammonia water.

 

2. Main technical parameters

SCR denitration unit is suitable for new or revamped units, and its typical performance data are as follows:

2.1. The NOx removal rate can reach more than 95%.

2.2. The escape rate of ammonia is less than or equal to 3ppm.

2.3. The conversion of SO2 / SO3 is less than or equal to 1%.

 

3. Equipment appearance and structural dimensions

See Table 1-1 for main dimensions of 300-1000mw SCR denitration unit

Table 1-1 main external dimensions of 300-1000mw SCR denitration unit (it can be adjusted according to specific project)

Item Data (typical)
300MW 600MW 1000MW
Reactor section size (width × depth) (mm × mm) 9640×8010 15400×10010 19240×12010
Module layout in reactor (block × block) 5×8 8×10 10×12
Dimension of boiler steel frame column grid (width × depth) (mm × mm) 34800×18500 46000×20500 55200×23000
Cross section size of vertical flue at reactor inlet (width × depth) (mm × mm) 9640×2500 15400×3000 19240×3500

 

4. Selection method

Denitration design is designed separately according to the specific situation of the project, and the model is only for reference. If fine selection is carried out, the following conditions must be met:

4.1. Natural environment of power plant.

4.2. Fuel characteristics.

4.3. General layout of power plant (including location and area of ammonia area, etc.) and geological report, etc

4.4. The specific position and structure of the equipment behind the last row of columns of the boiler, and the bearing condition of the foundation, etc.

4.5. Flue gas composition under BMCR condition of steel furnace and flue gas volume and temperature at economizer outlet under different boiler loads.

 

5. Scope of supply and ordering instructions

5.1. General requirements

The scope of supply and work includes process design, equipment manufacturing, equipment and material supply, transportation, installation (or installation guidance) and acceptance of main processes, commissioning guidance, technical services, personnel training, test, after-sales service, etc.

Conduct necessary technical training for the buyer's installation, commissioning, operation, maintenance and management personnel, and dispatch technical experts to participate in the performance assessment test organized by the buyer.

5.2. Scope of supply

The design and supply scope of denitration system is 1.0m outside the center line of the last row of columns of boiler and 1.0m outside the cofferdam of ammonia area Within the boundary, ammonia pipeline, steam pipeline, water pipeline, air pipeline, ammonia / air mixer, dilution fan, ammonia injection system, flue system, SCR reactor, catalyst, soot blowing system, ammonia storage tank, ammonia unloading compressor, ammonia evaporator, ammonia buffer tank, ammonia dilution tank, waste water pump, waste water pool, and the connecting pipes of various equipment and corresponding control equipment Electrical equipment, thermal insulation metal component outer guard board, paint, HVAC, fire protection, lighting, communication, grounding, lightning protection, fire alarm, cable tray, pipe support and other auxiliary systems and equipment in SCR reactor area and ammonia area are within the scope of supply.

The utility system of ammonia area includes spray water, industrial water, compressed air, steam pipeline, etc., which is connected by the design institute to 1.0m outside the cofferdam of ammonia area.

The ammonia pipeline between ammonia area and reactor area shall be supplied by the seller according to the total length.

5.1. Supply principle. The following are the supply requirements for process, electrical and instrument control parts.

5.1.1. Motors and common bases of all rotating equipment (pumps, fans, etc.) shall be supplied with the main equipment.

5.1.2. The actuator of all equipment (baffle, valve, etc.) shall be supplied with the main equipment.

5.1.3. All local instruments installed on the equipment, such as temperature, pressure (differential pressure) and liquid level measuring points, shall be supplied along with the equipment.

5.1.4. Unless otherwise specified, the materials, bolts, gaskets and supporting flanges required for fastening and installation of mechanical equipment and pipelines shall be supplied together with the mechanical equipment.

5.1.5. The paint of the equipment supplied shall be in good condition, and the weathering resistant high-quality paint shall be used. The paint for the equipment within the scope of supply and the steel structure, pipeline, support and hanger of the equipment body shall be the supply content of the seller. The paint materials for on-site repair are included in the corresponding scope of supply, and the on-site repair shall be completed by the buyer.

5.1.6. Provide random spare parts and special tools (including spare parts and special tools required for installation, commissioning, operation and maintenance during warranty period, as well as special tools required for the first overhaul).

5.1.7. The principle of supply subcontracting:

     ① Imported equipment and systems shall be adopted

     ② Equipment and systems supplied by domestic subcontracting;

     ③ Ammonia injection system;

     ④ All equipment and system pipelines shall be manufactured in the manufacturer according to the shipping restrictions and meet the requirements of China's highway transportation regulations;

     ⑤ All flanges, openings and nozzles shall be properly protected according to the industrial standard requirements to prevent damage, corrosion and impurity invasion during shipment and storage;

     ⑥ The screw joints and pipe ends shall be covered with metal or plastic covers to prevent impurities from entering and damaging the ends;

     ⑦ All bulk parts shall be packed and shipped, and each box shall be properly marked with identification marks;

     ⑧ Metal caps, fasteners or covers shall not be welded on any made parts.

5.2. The supply items are the corresponding systems and equipment, pipelines and valves of denitration device.

5.2.1. Helium unloading, storage and supply system: including all equipment and accessories from unloading compressor population to ammonia / air mixer (including ammonia / air mixer).

5.2.2. Ammonia injection system: including all equipment and accessories (including dilution fan) from the outlet of ammonia / air mixer to ammonia injection nozzle.

5.2.3. Nitrogen purging system: including all necessary equipment components, pipe accessories, etc. (excluding nitrogen cylinder).

5.2.4. Flue system: including supports and hangers, expansion joints and other components.

5.2.5. SCR reactor: including reactor shell, catalyst, support structure contained in shell, flue gas rectification device, sealing device, etc.

5.2.6. Catalyst handling system: including catalyst carrier, lifting device, slide rail, etc.

5.2.7. Soot blowing system: including all equipment components, relevant valve pipeline system and control equipment necessary for soot blowing system.

5.2.8. Instrument and control equipment.

5.2.9. Electrical system.

5.2.10. Steel structure of denitration device and platform escalator.

5.2.11. Thermal insulation and painting:

    ① provide insulation design, paint design and supply within the scope of supply;

    ② provide metal components and external protection plate required for thermal insulation, which are consistent with the boiler body;

    ③ paint the equipment in the factory, and provide necessary on-site repair paint.

5.2.12. Spare parts and special tools.