At present, the use of flow meters to measure steam flow, measuring medium refers to single-phase superheated steam or saturated steam. For the steam with constant phase change, there must be some inaccuracy in measurement. The solution to this problem is to keep the superheat steam, to reduce the moisture content of the steam, heat preservation measures such as strengthening the steam pipe, reducing the loss of pressure steam, in order to improve the accuracy of steam measurement. However, these methods can not completely solve the problem of inaccurate measurement of steam flow. The fundamental way to solve this problem is to develop a flow measuring instrument for measuring two-phase flow medium.

When the working state of the steam deviates from the design state, the flow indication will produce errors. It also affects the flow measurement, so the measurement of steam flow needs to be compensated, and the compensation factor is complicated because of the change of steam condition. Superheated steam density is determined by steam pressure and temperature of two different parameters, and the range of parameters, expressions of density is not the same, can not be expressed by the same formula, so cannot obtain the uniform density formula, only individual derived temperature and pressure compensation formula. In the range of temperature and pressure fluctuation, besides the temperature and pressure compensation, the expansion coefficient of gas should also be considered.

Regardless of the flowmeter detection of saturated steam flow in steam pressure fluctuation under the condition of pressure compensation measures must be taken, this is because in the flow equation, there are factors of steam density, working conditions and design conditions are not the same, the reading error will be generated, and the size of working pressure and design pressure deviation error, P >P will be negative error, otherwise there will be a positive error. Dry steam conditions is an important condition to accurate measurement of steam flow, currently being developed online steam quality measuring instrument, the degree of instrument applied to steam flow measurement and compensation system to be dry, will further improve the measurement accuracy. At present, the following three measures should be taken: (1) the steam transmission pipeline must have good insulation measures to prevent heat loss. (2) in the steam pipeline to block water, at the lowest point of the pipeline and the instrument before the pipe should be equipped with traps, timely discharge condensate. (3) boiler operation should avoid the phenomenon that the liquid level of drum is too high, so as to minimize the fluctuation of the load.

Solution application analysis

Selection and comparison of instrument for saturated steam flow

At present, with as many as 60 kinds of flow meters are mainly industrial, vortex flowmeter, differential pressure (Kong Ban, pitot tube, pipe) flowmeter, shunt type flowmeter, Annubar flowmeter, float type flowmeter. In history, there is no flow instrument suitable for any fluid, any range, any flow state, and any use condition. Any flow meter has its specific applicability and limitations. If the flow meter is not properly chosen, the flow must be measured incorrectly. But the flow measurement is a complicated technology, and many kinds of flow meters, even for a certain application, choose a suitable flow meter will become a highly technical work, need factors before making the final choice carefully and thoroughly consider and Quan Hengxu related measurement problems. Therefore, the correct choice of instrument is a key instrument in normal use, in the practical application, too much fault is due to instrument selection unreasonable, a detailed understanding of the field application of the operating conditions and the medium parameters, select the appropriate pressure, temperature, protection, explosion-proof grade and material structure, to ensure that the instrument can run in the best condition.

Steam metering should consider 5 main factors in the selection of flow meter: measurement methods, performance requirements and instrument specifications, measured fluid characteristics, environmental conditions, economic conditions (purchase costs, installation costs, operating costs, maintenance costs, expenses check). In our practical work, whether it is used for industrial and mining enterprises heating centralized production, is the most used orifice plate (nozzle) flowmeter and vortex flowmeter, based on the two meter as an example explained

Differential pressure flowmeter is composed of a flow detection element is installed in the pipeline in (which produce a differential pressure device, referred to as the instrument of differential geometry), known fluid conditions and a meter and a pipeline to calculate the flow meter, a pressure device, pressure pipe and pressure gauge is composed of three parts. The orifice flow meter as the representative of the differential pressure flowmeter application has a long history, high degree of standardization, the application is widespread, may not be the real flow calibration, differential display instrument standardization and serialization and high level of generalization, the theory of high precision, wide application range and strong adaptability, low initial investment cost.

But through practical application, it is found that the orifice flowmeter is also inadequate:

Many factors in the application (the design parameters and operating parameters are inconsistent, the upstream straight pipe length, orifice plate and pipe is not concentric orifice A surface contamination, sharp wear etc.) has great influence on the measurement accuracy, the measurement error increases, resulting in reduced accuracy. In particular, it is necessary to check the differential pressure loosening device to ensure the accuracy of the zero point, and check the three way valve regularly to prevent the measurement error caused by the blockage.

The installation quantity is big, the more trouble, and the demand is high, need regular maintenance and cleaning of the larger workload.

It needs to be equipped with differential pressure transmitter to increase maintenance work. Besides, the pressure pipe is needed, and the pressure pipe is to be insulated in winter

Boiler in operation, the liquid level is always changing. The main cause of the change of liquid level is the external disturbance and internal disturbance of boiler. When the external and internal disturbances, the material balance between evaporation equipment (i.e. evaporation and to balance the relationship between water damage, or refrigerant) state changes (volume of water and steam changes when the boiler pressure changes, resulting in a drum), liquid change. The magnitude of the change of the liquid level in the drum is related not only to the magnitude of disturbance, but also to the disturbance velocity.

The basic requirements of boiler drum level measurement system, according to the importance of boiler drum level measurement and the characteristics of measurement technology, the boiler drum level measurement system should meet the following basic requirements at least:

1. good accuracy as everyone knows, the boiler drum level relative to the main steam pressure and temperature of this kind of parameters, parameters are not accurate control, under normal circumstances, two drum level measurement value deviation is acceptable within 30mm. It is not very difficult to maintain such accuracy in normal conditions. However, because the drum level measurement object is very complex, and the drum level measurement principle or closed tube differential pressure measurement, the drum pressure and measuring the reference condition change will cause very large errors beyond the above requirements. Therefore, for a long time, to ensure the accuracy of drum water level measurement has been a difficult and key problem in front of us. Guangzhou South control instrument control equipment Co., Ltd solves this difficulty by differential pressure measuring principle!

2. maintenance good, boiler drum level measurement system maintenance should be simple, maintenance work should be as little as possible, and should be convenient for online actual water level signal protection linkage test.

Boiler drum liquid level measuring system

Size: T|T

Article source: South control instrument responsible editor: marketing department popularity: - Published time: 2013-01-24 17:51

The 3D map from South control instrument engineer, measurement and analysis of boiler drum level from the field service engineers and production technology department jointly elaborated, I hope to bring you help in the boiler drum level measurement.

Keeping the boiler drum liquid level in the normal range is an important safety index for boiler operation. The drum level varies frequently due to changes in load, combustion conditions, and feed water flow. As everyone knows, the level is too high or sharp fluctuations will cause deterioration of quality of steam and water, cause the heating surface of the salt, will cause serious damage to the turbine water impact vibration and blade; the level is too low will cause the failure of sewage, dosing furnace steam into the down pipe with steam, and even cause, effect of boiler water circulation conditions, resulting in a large area of furnace tube blasting. The accidents caused by the measurement and control of the liquid level of the steam drum often happen, and seriously affect the safety of the operation of the power plant.

In the boiler operation, we monitor and control the liquid level of the drum through the liquid level measuring system. When the drum level exceeds the normal range of operation, the alarm system will send out an alarm signal, and the protection system will take necessary protective measures immediately to ensure the safety of the boiler and the turbine. Therefore, the boiler drum liquid level measurement system is an extremely important system for the safe operation of the unit.

Sketch map of boiler drum liquid level measuring system

Boiler in operation, the liquid level is always changing. The main cause of the change of liquid level is the external disturbance and internal disturbance of boiler. When the external and internal disturbances, the material balance between evaporation equipment (i.e. evaporation and to balance the relationship between water damage, or refrigerant) state changes (volume of water and steam changes when the boiler pressure changes, resulting in a drum), liquid change. The magnitude of the change of the liquid level in the drum is related not only to the magnitude of disturbance, but also to the disturbance velocity.

The basic requirements of boiler drum level measurement system, according to the importance of boiler drum level measurement and the characteristics of measurement technology, the boiler drum level measurement system should meet the following basic requirements at least:

1. good accuracy as everyone knows, the boiler drum level relative to the main steam pressure and temperature of this kind of parameters, parameters are not accurate control, under normal circumstances, two drum level measurement value deviation is acceptable within 30mm. It is not very difficult to maintain such accuracy in normal conditions. However, because the drum level measurement object is very complex, and the drum level measurement principle or closed tube differential pressure measurement, the drum pressure and measuring the reference condition change will cause very large errors beyond the above requirements. Therefore, for a long time, to ensure the accuracy of drum water level measurement has been a difficult and key problem in front of us. Guangzhou South control instrument control equipment Co., Ltd solves this difficulty by differential pressure measuring principle!

2. maintenance good, boiler drum level measurement system maintenance should be simple, maintenance work should be as little as possible, and should be convenient for online actual water level signal protection linkage test.

Heating prepaid payment control system

A key to encourage industrial cogeneration as our government energy conservation, air pollution control, Guangzhou Nankong instrument control equipment Co. Ltd. will experience oil pipeline oil industry in transportation, construction of city pipe network applied in heating industry in. Wireless data transmission technology, such as flow, pressure and safety control in heating network, has won the good reputation of customers.

The first part is about the background and basis of the prepayment system in the heating industry

1, heating industry background

A key to encourage industrial cogeneration as our government energy conservation, air pollution control, Guangzhou Nankong instrument control equipment Co. Ltd. will experience oil pipeline oil industry in transportation, construction of city pipe network applied in heating industry in. Wireless data transmission technology, such as flow, pressure and safety control in heating network, has won the good reputation of customers. With the rapid development of cogeneration, central heating throughout, and rising coal prices, charging a series of problems gradually appear, should the requirements of our customers, the company in 2002 began the development of prepaid system and after 2-3 years of gradual improvement, was applied to the market in 2005.

2, though the prepaid system mainly solves the problem

2.1, large loss of steam measurement

As the heating industry, from the power plant pipe exports began to measure to each household measurement of the total total is always great difference, and some heating company balance even more than 10%, very normal. As a normal loss of transmission, if the maximum flow rate (flow speed of 15 meters / second or more), the maximum loss of the pipeline should not exceed 1.5%, if the excess measurement error of 1.5%, it shows that there is an abnormal loss exists. There are big errors in pipeline loss, mainly in the following aspects:

A. normal heat loss

The steam in the pipe, the temperature will gradually drop, produce a small amount of condensed water, this part of the condensate in the household metering instrument to measure, there is relationship between the flow velocity of condensed water and steam in the pipe, flow is large, the condensed water is less, the smaller the flow rate, the more condensed water. Belong to the normal loss.

B. metering instrument characteristic reasons, resulting in less count, leakage meter

At present, the steam measurement in the heating industry, because of its high temperature reasons, there are not many flow meters can be selected, mainly using vortex street, orifice, V, vertebral, bend four kinds of flow meters to measure. In addition to the vortex and V cone, the four flowmeters can reach the range of 1:10 to 1:15, and the range ratio of the orifice and elbow flowmeter is 1:3. Within the range of measurement meter, instrument can guarantee the accuracy of the measurement, but when using the flow is lower than the lower limit of measurement meter, the instrument will even without leakage; when the pipeline flow beyond the measurement range of the fluid, there will be a jet, flow meter is to measure instrument, the measurement data is far less than the actual flow. The following figure is a diagram of the range and range of the error of the DN100 vortex flowmeter:

C. caused by malicious steam theft

Steam prices from 96 years, 60 yuan a ton, until now 300 yuan a ton, the user tried every means to steal steam more and more, the means are also multifarious, the main means of stealing steam have the following several kinds:

1) use a big head to puncture the instrument signal line, cause the temperature, pressure or flow signal line short circuit, so as to achieve the purpose of stealing steam. When the temperature signal is short circuited, the temperature shows the normal temperature, the vapor density decreases, and the instantaneous flow decreases several times. When the pressure and flow signals are short circuited, the measurement value is zero and the flow rate is ignored or the density is decreased.

2) make use of the flow measuring range characteristic of the flowmeter, make a false statement of the gas consumption, cause the error of the flowmeter selection of the heating company, and make the instrument work in the lower or lower flow or the upper limit flow for a long time. Use the instrument's error to steal steam.

3) bribe the heating company's meter reading or maintenance personnel, modify the instrument parameters, resulting in fewer meters, so as to achieve the purpose of stealing steam.

4) malicious to the metering instrument power failure, so that the instrument does not work in use, thereby stealing steam. High steam prices, large amount of use, once the phenomenon of malicious theft of steam, the amount of huge losses.

2.2 malicious arrears and cash flow problems

Steam unit price is high, the average user is hundreds of thousands of dollars per month, or even millions of fees, once encountered bad customers malicious arrears, heating companies will fall into a passive situation. On the one hand, coal, see the money delivery, on the other hand, gas charges can not be received, once the formation of baggage, there will be cash flow problems. The prepaid system can put the money in advance before, the side can organize coal inventory funds.

The design and development of system 3, Sisson prepaid basis

3.1. Design standards and specifications

Hardware and software technology the scheme provided are in line with national and local laws and regulations, and in strict accordance with the requirements of ISO9001 quality assurance system to organize production and provide technical services, implementation of the latest version of the international standards, national standards and industry standards and norms, comply with environmental requirements.

The second part Nishimori theft proof prepayment control box function

Brief introduction of prepayment control box type anti-theft Nishimori function

Wireless remote transmission function:

Data upload: security control box prepaid Nishimori, built-in GPRS/CDMA wireless transmission module DTU, can easily be instantaneous flow, the user's cumulative flow, temperature and pressure, balance, valve opening, door opening and closing state information is uploaded to the monitoring computer room. At the same time, it can combine the configuration software of the upper computer to analyze the abnormity of temperature, pressure and flow, so as to judge the fault of the instrument, and avoid the customer to use the needle signal line to carry out the behavior of stealing steam, and realize the function of remote meter reading.

Instruction: through the monitoring computer, according to the accident occurred at the scene, remote valve closed, open, without any distance restrictions.

The alarm recording function of the out of doors alarm:

In order to avoid customer collusion overhaul, meter reader out of the box to modify the instrument coefficient, the control box is not only equipped with double locking facilities, but also has the function of unpacking alarm. Once the box door is opened, the system automatically uploads the time and state of the unpacking, and records it. At the same time, it can select the function of taking out the alarm and taking photos.

Historical curve storage function:

Nishimori theft proof prepayment control instrument Chinese screen, and storage temperature, pressure and flow rate of 365 days of history, once the accident disputes can easily check, and avoid cheating customers to steal steam.

Control instrument has automatic reporting function, daily reports, monthly statements, annual cumulative, convenient inquiry, meter reading.

Recharge record display function:

Record each recharge record, convenient for customers to check and check on the spot.

• ultra range shutdown valve function:

According to the measurement range of field instruments can be set beyond the range of valve in the range beyond the upper limit, prepaid control instrument will automatically close the small valve, the flow control in the flow range; in the measuring range or less than zero flow, the valve can be closed automatically according to the set value. In order to prevent users from exceeding the scope of stealing steam behavior.

Ultra automatic range compensation function:

According to the measurement range of field instruments can be set beyond the range of automatic compensation of losses in excess of the upper limit and the lower limit range, prepaid control instrument can automatically set the required compensation; compensation for losses caused by excessive process.

Overdraft authorization function:

According to customer credit, you can arbitrarily set overdraft authorization limit, in order to avoid non working hours due to insufficient balance to close the valve, causing losses to customers.

Insufficient balance alarm function:

The amount of charge fees to customers according to the amount of alarm, sound and light alarm in advance by user, and uploaded to the host computer, inform the user through the heating company telephone service personnel, to avoid affecting the normal use of the client.

Power off time recording function:

In order to prevent users from stealing by means of power failure, the control device is provided with a power-off recording function, which can record the last 30 power failures and the power on time, so that the inquiry is convenient.

UPS backup power function:

System settings backup UPS power supply, can continuously maintain more than 24 hours of power supply time. And inform the host system in time to pay attention to.

System overall structure design

A key to encourage industrial cogeneration as our government energy conservation, air pollution control, Guangzhou Nankong instrument control equipment Co. Ltd. will experience oil pipeline oil industry in transportation, construction of city pipe network applied in heating industry in. Wireless data transmission technology, such as flow, pressure and safety control in heating network, has won the good reputation of customers.

According to customer requirements can be integrated network, each site through the connection of 1 wireless transmission module, transmitted to the data center server. The monitoring system is constructed as shown in the following figure:

First, the hardware part:

Monitor host: use rack type U server, include 1 redundant data servers, 1 WEB servers. (22 inch LCD display) type: enterprise class: rack type structure: 4U

Processor: CPU type: XeonE7420CPU frequency: 2130MHz, with 2 XeonE7420 processors

Maximum number of processors: 4, process technology: 45 nm, three level cache: 8MB, CPU core: quad core (Dunnington)

Main board: FSB (bus):1066MHz, expansion slot: 7 PCI-Express slots (4 x8,3 x4)

Memory: memory type: FB-DIMM, memory size: 2GB, maximum memory capacity: 128GB

Storage: hard disk size: 2*146GB, hard disk type: SAS, hard disk maximum capacity: 1.5TB

Network: network controller: 4 embedded BroadcomNetXtremeIITM5708Gigabit5 Ethernet cards,

Interface type: standard interface: rear: 2 universal serial bus (USB) port 2, 9 pin serial port, video interface, Gigabit Ethernet interface for DRAC, with blue / orange lights LED ID button, the front 2: universal serial bus (USB) port 2, LCD panel with rolling system alarm the 15 pin of the video display, system interface, power on / off button, internal: 1 universal serial bus (USB)

Two 、 system software constitution:

When the user monitors the screen and data, the customer enters the user's own account number and password from the website. No matter when and where the customer is, as long as you can access the Internet, you can control the data at any time and place.

The main functions are:

24 - hour online operation, real-time acquisition of each user station temperature and pressure, flow and other operating parameters, operation of real-time monitoring of each acquisition meter, and the metering instrument malfunction can be found in a short period of time, and the failure time record record, to avoid the loss of measurement;

Carry on the operation analysis of the whole pipe network data, have powerful statistics and database inquiry function, can inquire the steam consumption situation of any user at any time; analyze the pipeline damage in real time and effectively;

• alarm the user, the city power outages, abnormal collection of parameters, and record for future reference;

• generate settlement bills (daily, monthly and annual reports) as required and print them directly;

The function of chart curve can reflect the steam consumption of each user intuitively;

Network design, support remote access function;

The combination of real time database and relational database ensures the stability and security of data.

Powerful software functions, combined with high-performance, low bit error rate data communication equipment, and UPS uninterrupted power supply design, to ensure the stability of the whole system performance.

Sewage metering system

I. overview

Nowadays, with the improvement of productivity and the modernization of expanding the scale of production, relates to the field increasing, the kind and quantity of used resource increased rapidly, which brings serious environmental pollution problems in the world. Along with our country but to the whole world on the environmental protection issue, environmental management and protection is accelerating, in order to more effectively promote the work of city planning and pollution control, is in urgent need of sewage discharge on the industrial "three wastes" of the comprehensive management and control and. Therefore, accurate measurement and verification of sewage flow has become a very necessary basic work. At present, domestic wastewater treatment plants are responsible for the discharge of industrial wastewater, mainly using the "mud and water integration" sludge treatment and disposal technology, and constantly updating the treatment technology at any time

This installation diagram is for reference only

This sewage metering system used in sewage flowmeter FLDC series South control instrument production (electromagnetic flowmeter) total pipeline measurement sewage pond water flow, the inlet flow and outlet liquid flow (two sets of electromagnetic flowmeter with each filtrate machine); installed in the control room of XSFT general type flow meter for display instantaneous flow and cumulative flow meter all; BST6600-LT series single flange pressure transmitter for measuring the pressure of pipeline (range: 0-2.5MPa and 0-4MPa), followed by XSPI intelligent regulator, 4-20mA regulator control output inverter, to control the pressure of pipeline.

In addition, the AD3800 series ultrasonic level meter for measuring level and mixing tank dosing tank, the range is 6 meters and 8 meters), this link is due to the stirring rod inside the tank, so use the AD3800 series ultrasonic liquid level gauge errors, our proposed treatment plants have the economic ability of the South can consider using the AD113 series control radar the production of a physical instrument or Dan Falan BST6800-LT series liquid level transmitter to solve this problem.
 

Three 、 site installation drawing

Sewage water inlet pipe DN200 sewage flowmeter

(installed here is the FLDC series of sewage meters produced by the South control instrument. The lining is made of polytetrafluoroethylene and measures the flow rate of the main pipe inlet.)

Plate and frame filter press, filtrate drainage pipe, DN150 sewage flowmeter (electromagnetic flowmeter)

(installed here is the FLDC series of sewage meters produced by the South control instrument. The lining is made of polytetrafluoroethylene, mainly used to measure the flow rate of the intake and outlet of the press filter)