Buy chemical pump afraid to be pit to see China's first full chemical pump procurement guide and practical experience come out

For the newly arrived pump purchasing manager, just familiar with the product knowledge must take up a lot of work time, pump according to industry, principle, medium, use, structure, assembly, drive, material, performance classification unlimited segments Continue to estimate or let the purchasing manager can not find the beginning of the North. In view of this, the Asian pump net Xiaobian meticulously prepared this article, "buy chemical pump afraid to be pit to see China's first most complete chemical pump procurement guide and practical experience come out" solution to pump managers urgency! Most of the chemical pump procurement through bidding, how to ensure that the performance of the procurement of pump units meet the technical requirements, reliable quality, and to minimize project investment, engineering companies and manufacturing plants is the common responsibility. This article brings together part of the experience and lessons learned in the preparation of the preparation of bidding technical documents, preparation of bidding technical documents, manufacturers technical documents and other procurement process, and lists a number of engineering cases to be analyzed, hoping to improve the technical level of both buyers and sellers help , To jointly promote the success of chemical pump procurement. Inquiry technical documents compilation stage ■ should ensure that the source of pump inquiry technical documents complete, correct and reasonable, is the engineering company moving equipment professional duties Pump inquiry technical documents by the engineering company or design institute of mobile equipment professional preparation, Editors should first review the process, system, electrical and other professional submitted conditions are complete, correct and reasonable, if necessary, should coordinate with the relevant professional, clarified or amended, which is to ensure the quality of inquiry technical documents. If not enough attention to this review, and sometimes caused by the purchase of the pump is not economical, or even can not use, to name a few engineering cases. Case 1: The pump data sheet is not marked on the media composition, resulting in imported pitot tube pump accident, compensation for foreign redress. More than a decade ago, a urea condensate pump technology project, professional process conditions, the media is only written as the process of condensate, the pump data sheet did not indicate the media composition. A Pitot tube pump manufacturer in the United States will seal the O-ring material for the high-grade fluorine rubber, the first put into operation shortly after the leak occurred machine seal leakage, motor overload jumps. Pump disassembled and found O-ring has been severely damaged, because the pump bearing deformation has stuck stuck. Foreign investors have already paid for the accident. In fact, the root cause of the accident is the process of condensation of ammonia, O-ring instead of domestic cheap nitrile rubber machine seal no leakage. As the author of the inquiry pump data table lax check, did not mark the media composition, should bear the primary responsibility, foreign injustice. After this lesson, "Viton acid and alkali-resistant" feature makes the author unforgettable for life. No media components are marked on the pump datasheet. In particular, components that may cause stress corrosion cracking such as hydrogen sulfide, chloride, fluoride, and cyanide should not be missed (even in trace amounts). This is the correct choice of material for the pump overcurrent and seal components. Case 2: Foreign craft patent dealer pyrolysis gas chilled water pump medium carbon black mistype typing 13mm, resulting in pump and machine sealing program blunder, great economic loss. In the previous year, an MDI project natural gas pyrolysis gas pyrolysis gas pump, flow 1831m3 / h, lift 60m, the transmission medium is water (containing 0.3wt% carbon black), a number of 16 units. The well-known technology patent provider in Europe submitted media conditions, mistakenly typing carbon black particles from 13μm to 13mm. Inquiry Pump Data Sheet Set Impeller as Open, Seal with Dual Seal, Flush Plan Plan 53A. From the process flow chart shows that the pump is used for acetylene cracked gas screw compressor cooling water, flushing water recycling, since a large number of flushing water to enter the compressor, the machine seal chamber to allow clean water rinse. The Plan 32 solution has been used successfully for many years on multiple sets of natural gas acetylene units in the same process and is the most economical and reliable solution. Transport medium water, the amount of carbon black is very small, very small flow pyrolysis gas pyrolysis pump are closed impeller. Buy chemical pump afraid to be pit to see China's first most complete chemical pump procurement guide and practical experience come out argument This project case to our lesson is that we must dare to veto programs unreasonable foreign companies to adopt the proven test of mature programs. ■ The inquiry pump data sheet should include a "height of the horizontal axis of the pump to the lower surface of the base" added to the engineering data sheet and "NPSHa reference is the base of the pump base." IMPSH3 benchmark: API610 standard and SH / T 3139-2010 petrochemical heavy duty centrifugal pump engineering specification has been clear that the horizontal plane of the pump shaft centerline; vertical suspension pump reference plane for the pump base Of the vertical; vertical pipeline pump reference surface for the inhalation center line. NPSHa Benchmark: According to the Engineering Company Design Manual, the benchmark for calculating NPSHa is the pump's top surface. Therefore, for horizontal pumps, the NPSH3 and NPSHa standards should be uniformed. An increase of "the horizontal axis of the pump shaft to the lower surface of the base" should be added to the data sheet of the already-established pump of each engineering company, fill in. Case 3: Two sets of high-boiling bottom pumps with an annual output of 100,000 tons of BDO units. The tender pump factory did not pay attention to the baseline of NPSHa on the inquiry pump data sheet. The selected pump did not meet the requirements of the initial inquiry pump data sheet. Initial Inquiry Pump Data Sheet Conditions: Nominal inlet pressure O.78bar.A, vaporization pressure O.097bar.A, rated flow 2400m3 / h, lift 52m, NPSHa = 5m Bidding conditions: ZE400-8728,980RPM, NPSH3 = 4.5 m After the NPSH3 and NPSHa benchmarks are unified for the pump shaft centerline, the bid pump does not meet the requirements of the initial Inquiry Pump data sheet. By the professional equipment and professional coordination system, an increase of NPSHa, bid OH2 single suction pump can fully meet the requirements of anti-cavitation. API610 standard version 8-11 edition, in addition to the medium temperature pump industry in our country widely used API pump introduced Sulzer Z series pumps, ZA-type design pressure 25bar, pump body for the foot support, such as the use of centerline support, to be changed With a design pressure of 50bar ZE pump, (we welcome the attention of WeChat: Pump Friends ring) and the majority of the project pump working pressure is less than 25bar, such as the full implementation of the API610 standard requirements, a substantial increase in pump costs, especially precious materials pump . US ANSI / ASME B73.1-2001 "Technical Horizontal End-suction Centrifugal Pump Technical Specifications", the pump body all use the foot support, Article 4.1.2, the temperature limit is less than 260 ℃. API610 version 7 provides that the horizontal fluid pump fluid temperature> 177 ℃ should be supported by the center line of the pump body. The eighth edition of the pump instead of all the centerline support is intended to completely heat the rotor and the pump body, not the media temperature, a small gap mouth ring, throttle ring, etc. do not touch. However, such as the medium temperature is not high, the pump casing is not high horizontal center of the pump, pump foot support is also safe. Example: ZA80-160, pump housing center height 200mm, the medium temperature llO ℃, ambient temperature 20 ℃, pump casing with a larger thermal expansion coefficient of austenitic stainless steel, the bottom of the pump shell support the center of the amount of upward thermal expansion: bearing box work Temperature 80 ℃, the rotor center upward thermal expansion: the difference between thermal expansion of 0.31-0.12 = 0.19mm. According to the model pump impeller port ring diameter, check API 610 Table 6, the minimum operating diameter clearance of 0.43mm, radius clearance of 0.215mm, the mouth ring will not collide. Chengda company on the medium temperature is below l00 ℃, the pump casing center height of not more than 200mm horizontal pump, such as the use of API 610 standards, pump inquiry data sheet selected OH1 type, not OH2 type. Case 4: Why NPSHa small high-flow pump OH2-type single-suction pump does not occur cavitation A project of two sets of annual output of 100,000 tons of BDO device 4 each a total of 16 high-temperature medium circulation pump, NPSHa The difference between NPSH3 and just meet the anti-cavitation requirements, the choice of low-cost OH2 single suction pump. Later found that if the NPSHa benchmark raised to the pump shaft centerline, can not meet the requirements of anti-cavitation, in order to eliminate this fear, re-study of the system of professional NPSHa calculation found NPSHa system conditions are very conservative . After the test of industrial operation, there is no concern about the cavitation performance of these large flow OH2 pumps. We find NPSHa conditions abundant in abundance for many projects due to: (1) The lowest level of pump suction side equipment taken by engineering firm NPSHa, sometimes lower than the level transmitter alarm (2) In the NPSHa calculation, the pressure drop of the suction pipe of the pump is set at a rated flow rate. If the rated flow rate is 1.1 times of the normal flow rate, the pressure drop will be expanded to 1.21 times, causing the NPSHa to decrease. NPSHa to increase; (3) Professional equipment press "pump inlet pressure minus vaporization pressure in addition to the proportion of the medium, then leave the safety margin is NPSHa" formula and found that the safety margin of the system specialist NPSHa sometimes made far greater than 0.6m. In addition, NPSH3 is the required NPSH at 3% loss of head (multistage pump is the head of multistage pump) determined by the test at ambient temperature, which is higher than the critical NPSH 0.3m. According to the cavitation thermodynamic factors, the same pump, NPSHa the same, the higher the water temperature the less prone to cavitation [1]. Liquids other than water, such as hydrocarbons, are less prone to cavitation than normal-temperature water. According to API 610 standards, this margin is not considered. Therefore, engineering companies should avoid NPSHa from the source too conservative or incorrect, try not to use slow pump, try to use OH2 single suction pump without BB2 double suction pump to create the conditions to optimize pump selection and reduce project investment. Buy chemical pump afraid to be pit to see China's first most complete chemical pump procurement guide and practical experience excuse ■ inquiry pump data table should not be about the pump type die, allowing the pump factory reported a different pump, is conducive to engineering companies Compare. Case 5: Iso-octane unit Super large size 20 alloy Sulfuric acid pump A device Six super large Alloy 20 sulfuric acid pump Inquiry data sheet provides impeller with double support, pump plant according to BB2 type bid; and B the same process equipment The No. 20 alloy sulfuric acid pump inquiry data sheet does not provide for the pump type, pump plant by OH2 bid. Buy chemical pump afraid to be pit to see China's first most complete chemical pump procurement guide and practical experience come out that we can see from Table 1, OH2 type is significantly better than the BB2 type: (1) large BB2 double suction pump 20 alloy pump casting Difficulty, due to delays in the delivery of the pump manufacturer, affecting the entire device can not be put into production as scheduled, forcing users to urgently domestic well-known pump factory manufacturing two 316L pump BB2 pump device for driving purposes. (2) OH2-type single suction pump reduces the pump body, reducing the difficulty of the 20 alloy pump casting, pump weight reduced by half, the pump price dropped. (3) PLAN 53B double-end machine sealing price is high, OH2-type single suction pump seal half, half the shaft seal leakage. Buy chemical pump afraid to be pit to see China's first most complete chemical pump procurement guide and practical experience comes out to say In order to improve the reliability of OH2-type impeller cantilever pump, the pump factory has taken two measures: (1) OH2-type bearing ratio BB2 large 4 block (bearing diameter increased from 100 to 130), the shaft thick, double the bearing life. (2) Shaft with high strength corrosion resistant duplex steel 2205, yield strength ≥ 450MPa, import pump 20 # alloy shaft yield strength of 2.65 times. Guangxi isooctane plant has been put into operation for more than six months, super-large No. 20 alloy acid circulation pump is operating normally. Another set of new users of isooctane plant in Guangdong to field research in Guangxi, also ordered the pump plant OH2-acid circulation pump. Case 6: Two sets of BDO plant with an annual output of 100,000 tons for a certain project in 2011 OH2 pumps were selected for the key large pumps of 16 large flow pumps, which saved a lot of investment compared with the BB2 double suction pump. The project's two main BDO plant processes have four key 16 key pumps (concentrated bottom pump, salt tower reboiler pump, low boiling tower reboiler pump, high boiling bottom pump) flow 1310 ~ 2400m3 / h, head 38 ~ 52m. Professional equipment analysis and comparison of several well-known domestic pump OH2 and BB2 two pump-type product performance, even in the BDO devices have no flow of similar performance, the preselected model pump performance in other chemical and petrochemical projects, there can be a few Home pump plant to compete, so inquiry pump data sheet does not specify the pump. Bidders on the technical and business documents after the competition, winning three pump plants are OH2 type. The test of 16 key large-flow pumps undergoing industrial operation was successful, saving a lot of investment for users. I firmly determined the first choice of large flow pump OH2 type, not easy to use BB2-type confidence. Project Case 7: The wrong solution of selecting centrifugal pump for small flow and high viscosity pump of PTMEG project has been corrected. When the high viscosity fluid is transported by centrifugal pump, the efficiency drops obviously. The higher the viscosity is, the more the efficiency is decreased. The smaller the same viscosity and flow rate, The greater the decline in efficiency. Therefore, the small flow of high viscosity medium should be used rotor pump. A group of PTMEG projects of the previous year included a group of low-flow and high-viscosity pumps, and a well-known U.S. patent holder insisted on using a centrifugal pump. Users also worry that we proposed to switch to the rotor pump in the event of a program performance test error, still using the centrifugal pump, causing great economic losses: (1) low efficiency, high energy consumption P9508ABC filter feed tank Pump (flow 6m3 / h, head 189m, viscosity 114Cp, density 893kg / m3), for example, the rotor pump and centrifugal pump inquiry shows: centrifugal pump shaft power and motor power are 10 times the rotor pump, More than 330,000 yuan. (2) Overheating of the polymer may result in degradation of the product and greater economic loss. Due to the low efficiency of the high-viscosity low-flow centrifugal pump, all energy losses are released into the liquid as heat, except for external mechanical losses. Deducting the pump heat will heat the medium, the polymer may overheat and lead to product degradation. The rotor pump, high efficiency, there will be no polymer overheating problems. (3) Need to set the temperature, alarm chain instrumentation According to the provisions of the patentee, to monitor the centrifugal pump temperature rise in the media, dozens of pump body temperature sensor installed, and set alarm instrumentation, costly, but this Can not solve the root cause of overheating of the medium. (4) filter feed pump screw pump than with a centrifugal pump reasonable In a filtering period, the filtration pressure gradually increased, such as centrifugal pump, the flow will gradually decline, unless driven by a variable frequency motor; and with a screw pump, feed The pressure will automatically rise synchronously to keep the feed flow constant. (5) Need to set the minimum flow protection circuit To protect the small flow centrifugal pump, set the minimum flow protection circuit, energy consumption and investment are increased. The rotor pump does not need to set the minimum flow protection circuit. In the area where the patentees can not intervene, the small-volume high-viscosity pump uses a rotor pump, which has been successfully operated with obvious economic benefits. In the following several PTMEG projects, foreign patentees began to accept the rotor pump program. ■ Specified inquiry pump data sheet materials should pay attention to the European and American markets 316SS stainless steel pump price is lower than 304SS, as a blind from the European and American patent providers on the material will cause economic losses (see Table 2) The first full chemical pump procurement guide and practical experience comes out that the pump body and impeller often castings, the domestic is often written as profile grades inappropriate, should use the internationally accepted castings grades, grade 8 that carbon content is extremely Eight; 3 that carbon content of three ten thousandths, for the low-carbon type (L); M said Molybdenum, very good mind. The role of molybdenum in stainless steel is mainly to improve the corrosion resistance of reducing media (phosphoric acid, acetic acid, organic acid, urea), and the ability of resistance to pitting and crevice corrosion. European and American pump industry batch production of stainless steel castings for the CF8M, chemical pump samples without CF8, select CF8 to separate casting, to increase the price. Affected by the standard materials on some Japanese chemical pump samples as well. This is why many imported items in our country, European and American patentees on the stainless steel pump just clean and no corrosive or light corrosive medium, the material used to mark API610 standard material code "A-8", namely CF8M, 316SS. Understand the 304SS pump on the market in Europe and the United States but the status quo than the 316SS pump expensive, it should be based on the purchase of the pump to determine the grade of stainless steel. Such as pumps in the European and American markets, with CF8M, 316SS; such as procurement in China, it should be changed to CF8,304SS; If you are not sure where to purchase, it should be changed to "A-7", austenitic stainless steel, including CF8, 304SS, CF8M, 316SS. ■ Actively organize design return visits to end users, incorporate practitioners' design improvements into new engineering projects, and prepare technical inquiries for pump inquiries. Project Case 8: Semi-lean liquid ammonia pump and hydraulic Turbocharged set drive cooling, resulting in waste, should be canceled. Chengda Engineering Co., Ltd. has adopted a single-drive semi-lean liquid pump-hydraulic turbine unit without auxiliary motor on more than 10 synthetic ammonia plants. According to the design conditions of KBR company, semi-lean liquid pump and hydraulic turbine seal are normal Run, with 55 ℃ -70 ℃ lean liquid rinse, no rinse liquid cooler. Due to the driving of the device, the pressure of lean liquid is not enough, it is necessary to use 104 ℃ or 133 ℃ boiler feed water, set the driving machine seal cooler, auxiliary motor with double-drive type unit is correct. However, for a single-drive unit, the actual operation of the device indicates that the drive of the hydrostatic turbine can drive the semi-lean liquid pump to reach the minimum lift only when the operating pressure of the absorber is lower than the design conditions, so the device drives Early use of only two electric units. Hydraulic turbine with commissioning conditions, the liquid pressure is enough, there is no need to seal cooler. (Welcome attention WeChat: Pump Friends Circle) users have already told me this experience, but the school inquiry quotation data table did not set the note on the car cooler with the machine removed, the unit imported from abroad still with the machine seal Cooler and piping, resulting in a waste, this is the author's failure. Pump inquiry price technical documents should be accompanied by a standardized "pump summary table", set out the necessary data to select the parameters and pump performance price parameters, will help speed up the tender and bid evaluation progress. Pumping all pumps together, when compared with each other, can sometimes be found in the upstream professional conditions typing errors or unreasonable, from the source to ensure that the pump inquiry data is correct. This pump summary can also be used as a pre-pump equipment, moving equipment to submit professional design conditions (see Table 3). Buy chemical pump afraid to be pit to see China's first most complete chemical pump procurement guide and practical experience come out that the preparation phase of the bidding technical documents pump guidelines: not only to meet the requirements of the tender documents, but also to achieve the selected pump low cost , For the user investment, reduce energy consumption. First, read carefully and fully understand the requirements of the bidding documents, especially the details that affect the performance and price of the pump, as well as the specifications in the pump datasheet. Pump selection should be more programs to improve competitiveness. Here are some excellent and mistakes in the case. Case 9: Adding a front pump to solve the cavitation problem, using the fast scheme, the BB4 pump of No. 6 is superior to the high pressure ammonium pump of Nissan's 1750 ton urea unit at an EPC export project of medium-speed BB5 pump. Inquiry conditions: the transmission medium is ammonium carbamate solution: to buy chemical pump afraid to be pit to see China's first full chemical pump procurement guidelines and practical experience come out that because of the high vapor pressure of ammonium carbamate solution, A plant program is BB5 type pump with 2980rpm speed; and B plant with 8457rpm high speed BB4 type pump, an increase of a booster pump, with a motor delay (see Table 4). Buy chemical pump afraid to be pit to see China's first most complete chemical pump procurement guide and practical experience comes out B plant program speed is high, the impeller series is half of plant A, the pump is to use the BB4 lower manufacturing costs than the BB4 , Only one more front-end booster pump with shaft power of 11.7kW was used to solve the cavitation problem of high-speed centrifugal pumps, so the bid was much lower and won the bid. Project Case 10: Pump selection should be more programs. Small flow pump. Do not choose only a small-caliber pump. Choose a block size caliber pump, and sometimes the outer diameter of the impeller can be a small block. Efficiency. Pump prices lower. Two identical PTMEG units in Xinjiang and Sichuan are located at p9304: flow rate of 12 m3 / h, lift of 75 m, viscosity of 88 cP and specific gravity of 1.03 (see Table 5). Buy chemical pump afraid to be pit to see China's first full chemical pump procurement guide and practical experience comes out to say the pump weight is the impeller diameter, not the flange diameter. Project B choose a large aperture block pump, impeller diameter of a small block. Advantages: (1) high pump efficiency, 23.6% vs 12.8%, high 10.8 percentage points; (2) shaft power, 10.7kW vs 19.7kW, less 9kW, the annual operating costs savings of 36,000 yuan; Project Case 11: Speed ​​technology, in a single loop to cancel the control valve, multi-loop or large operating range, should be studied frequency control and valve combinations optimization program to maximize energy efficiency. Pitot tube pump flow is smaller, the higher head, the more obvious technical advantages. Pitot tube pump is characterized by two major pump casing and impeller rotation as a whole, the liquid kinetic energy without disk friction loss (rotary shell pump); Pitot tube and then use the kinetic energy into pressure energy (pitot tube pump), China will This pump is called a rotary shell pump or rotary jet pump. Pitot tube pump gearbox is usually the growth rate, Jiangsu sea lion pump company started the late development of the rotary shell pump, but soon will be used to increase the speed of gearbox inverter motor speed, as the company hundreds of rotary shell pump The main configuration. Later, the company found that the inverter motor drive not only canceled the gear box and a set of coupling, the unit shortened, such as the original control valve to the control valve sent to the inverter can cancel the pump outlet pipe on the control valve to eliminate In the control valve on the energy consumption, the choice of pump head is also reduced accordingly, and save the cost of regulating valve maintenance [2]. According to Section VI-A58-87 of the "Chemical Engineering Handbook" used by our engineering firm, "Pressure Drop Assignments to Control Valves (Variable> Pressure Drops (including Control Valves> Of the value of 25% -50%, its value greater than or equal to 70kPa, in order to ensure the reliable operation of the control valve, but also a good quality of regulation. "[3] At present, frequency control technology has matured, high speed inverter motor quality has been reliable, Inverter prices have dropped significantly, the engineering company's moving equipment professional and process systems should work closely with professionals should not only use a single control valve. In the single-loop operation is not large, the use of frequency control technology, cancel the control valve , Energy-saving and saving effect is very obvious.For multi-circuit or large operating range occasions, according to the composition of the process system, the operating range of the degree of change, the pump characteristic curve, the characteristics of piping system, frequency control and Control valve combination of the optimal control program to achieve maximum energy savings, but also to ensure the flexibility and stability of the system operation [6] Pumping plant should pay attention to Sulzer Z series pump mechanical design allow Pump at 3600RPM speed safe use, bidders press 2950RPM performance curve selection, such as Hmax & pide; H amount is less than 1.05, switch to the first block of the pump, reduce the efficiency of valuable materials, pump prices and can be re-reported a frequency Motor speed program, the bid price but lower.On the contract technical attachments, if the pump set up a control valve, you can cancel, according to the system professional centrifugal pump calculation table pressure drop on the control valve to determine whether the pump specifications can be reduced. Frequency conversion motor base frequency down and step down, the centrifugal pump can be started with a load, the starting current is small, high-power motor start small impact on the power grid. ■ Centrifugal mucus pump with a higher rotational speed American Society of Hydraulic Engineers old standard performance correction did not consider the speed Some people think that viscosity is high, friction loss is high, centrifugal pumps that deliver mucus should use slow speed, and it is correct that mucus is delivered to the same pump with increased friction when the speed is increased; however, For the specified flow, head and liquid viscosity, the design unit or user sometimes provides slow pump is wrong. Centrifugal pump theoretical lift and mechanical loss of the basic Unaffected by the viscosity, the increase in shaft power while pumping mucus is primarily due to disc frictional losses, and the impeller diameter is inversely proportional to the square of the rotational speed for the required lift, which can greatly reduce disc friction losses. Tests and the new American Society of Hydraulic Formulas show that as long as the NPSHa-NPSH3 (NPSHa-NPSH3)> 0.6m cavitation prevention conditions, the speed of high shear force has no effect on the mucus, the centrifugal mucus pump should be higher Speed, this view of the mucus pump selection of economy and rationality has important guiding value.Company technical documents evaluation phase ■ evaluation of manufacturers technical documents, both to the inquiry technical documents, but also to accept the reasonable deviation from the bidders , The courage to amend the inquiry file may be wrong or wrong data, the ultimate goal is to purchase reliable and economical products such as the implementation of API610 standards, at rated flow, the maximum diameter of the impeller lift to reach the rated head of at least 1.05 Times, will result in a substantial increase in pump costs or reduce efficiency, engineering companies should allow deviations, as the case may be. AW610 standard and SH / T3139-2010 petrochemical heavy-duty centrifugal pump engineering specifications are not allowed to use the maximum diameter impeller should be able to replace the impeller or a different impeller hydraulic model, the pump should be able to increase at least 5 % Of the head. The author often found in the bid evaluation, such as completely not allowed to deviate from this provision, sometimes very uneconomical. For example: flow 340m3 / h, lift 135m, the proportion of 1.1 media. With ZE150-315,2950RP, efficiency of 75%, shaft power 183.3kW, impeller diameter of 318mm, the maximum diameter of 324mm impeller at a flow of 340m / h when the lift is 140m. 140 & pide; 135 = 1.037, does not meet the AW610 standard requirements. If the switch to the first gear of the ZE150-400, 2950RP, efficiency of 72%, shaft power 191kW, the annual operating electricity increased 31,000 yuan, pump weight increased from 240kg to 317kg, an increase of 1.3 times. The current tendency of engineering design is heavy safety, saving investment and designer personal relationship is not big, asking pump data sheet on the head of a large amount of wealth, resulting in most of the pumps are not daring to open the export valve, throttling caused by the export valve The serious waste of energy is a worldwide phenomenon, so that the 11th edition of the API 610 standard has changed the acceptance test tolerance of the centrifugal pump and the negative deviation (increased from -2% to -3%) for the pump with the highest amount of lift "150m and reduced the positive deviation (from + 5% to + 3%). China Chemical Engineering Survey and Design Association, "Chemical Design Manual," the sixth book (process system, professional pump calculation table set forth in the pump pressure up the regulation of the park should not be implemented.The set of manuals is China's chemical industry design institutes to break the traditional Design system to absorb the international advanced design procedures and methods, organized by the Ministry of Chemical Industry nearly a hundred people, the United States Kellogg Engineering Company based on the design specifications for the blueprint prepared to become our country Chemical Engineering Design Institute to implement the new system design, to engineering company The basic documents. The implementation of more than 20 years, some provisions to be amended. The system of professional pump calculation table is used to calculate the pump inlet and outlet pressure, NPSHa and other parameters, the table states that "pump pressure up rounded: tens digit less than 50kPa 50kPa, greater than 50kPa take lOOkPa. "For 500kPa differential pressure pump (specific gravity of 1, lift 50m), the maximum positive deviation of up to 10%, pump head smaller, positive deviation greater. Engineering companies have not implemented.If the implementation of API610 standard motor power factor of richness of the provisions of the proportion of less than 1 or conveying medium, will cause the motor power If necessary, the bidder should be allowed to provide two kinds of motor power options for the buyer to choose. API610 standard motor rated power richness of the provisions of the motor rated power ≤ 18.5kW 1.25,22 ~ 55kW to 1.15, ≥ 75kW 1. Some centrifugal pump engineering requirements also require: motor rated power should be greater than the rated power of the pump multiplied by the rich coefficient, or the maximum power on the supply impeller shaft power curve by the media weight, whichever is the greater .For the rated flow ratio BEP Pumps with a much smaller flow rate may cause the motor rated power to be unnecessarily oversized if the above regulations are implemented and the API 610 standard also recommends that the seller provide motor power alternatives for buyer approval For media with a transmission weight much less than 1, To select the motor, the motor will cause the rated power is too large. Can choose a smaller rated motor, the pump plant test with high-power motor, the user site test is mainly to check the mechanical operation is qualified, should be fixed on the pump outlet valve Permanent warning signs to write "water test run, the export valve is strictly prohibited to prevent large motor overload." Strive to avoid common errors or defects in bidding technical documents to improve the level of tender documents Centrifugal pump performance curve is the primary basis of documents should be focused on review Bidder in the centrifugal pump data sheet to fill in a lot of data are from the performance curve, (1) Some of the tender pump performance curve of the lift curve is only one, the chart did not indicate the rated conditions of the vertical lines and horizontal lines, can not determine the diameter of the selected impeller is in line with the provisions of the standard (2) HQ curves of the largest diameter impeller, selected diameter impeller and smallest diameter impeller should be on the map. (2) When the lift of the largest diameter impeller does not reach 1.05 times of the rated lift at rated flow, individual bidders will change the maximum diameter The lift curve of the impeller moves upwards and can be found in comparison with the standard performance curve of the same type of pump printing plate. (3) Note that the benchmark of NPSHa on the inquiry pump data sheet is the top surface of the pump, and the standards of NPSH3 and NPSHa are not unified , This is a common phenomenon, but also with the inquiry centrifugal pump data sheet did not emphasize the need for engineering companies in the inquiry pump data sheet to add a "horizontal pump The center line in the end under the seat height of the surface ", and indicate NPSHa benchmark. (4) When the NPSH3-NPSHa benchmark is unified, individual bidders reduce the NPSH3 curve if (NPSHa-NPSH3) is less than 0.6, which is lower than the NPSH3 curve for pumps of the same model at other pump plants. (5) When the maximum power of the selected impeller shaft power curve multiplied by the medium weight is greater than the rated power of the motor, individual bidders truncate the right end of the shaft power curve and the flow rate at the right end point is obviously smaller than the right end point flow of the impeller's head curve. Centrifugal pump viscous media or suspension performance correction does not attach importance Medium viscosity greater than 20 centipoise or with solids, the bidding pump flow head and inquiry the same value, did not pay attention to inquiry pump data sheet Note in the note, not carried out Correction of pump performance. Inquiry pump data sheet to submit the performance curve of viscous media and factory acceptance with the corresponding water performance curve of the two maps, more than two pump drawings submitted by the plant failed to close the zero flow is not equal to the head is obviously wrong. Grasping the influence of liquid viscosity on the performance of centrifugal pumps and the latest standards of centrifugal slurry pumps, the software for the preparation of computerized calculations and automatic generation of the performance curves of mucus can help to speed up the bidding process and raise the level of China's pump industry [4] [5]. Pump outlet pressure is greater than the inquiry material, the maximum allowable working pressure of the working pressure Z series pump design pressure: ZA type is 25bar, ZE type is 50bar, ZF type is 75bar, ZU type is 135bar, which refers to the carbon steel At room temperature, the maximum allowable working pressure, while the austenitic stainless steel, the pump allows the maximum working pressure dropped significantly. Some bidders did not check all kinds of PT pump map, the pump outlet pressure is greater than the inquiry materials, the maximum allowable working pressure of working pressure. The mechanical seal conditions table and seal cavity pressure is not enough attention to the chemical pump machine seal type and flushing program to determine the reasonable, economical, and mechanical seal conditions are correct and complete, pump factory and machine factory coordination is in place a great relationship . Pump shaft seal chamber pressure is to determine the seal seal hydraulic pressure basis, but most of the information in the pump factory did not provide the pressure of the pump shaft seal cavity, often resulting in pressure too high, or on the graphite seal ring erosion , Shorten their life, or no pressure on the device sealing liquid. Pump pressure is based on the type of pump structure and pump inlet and outlet pressure to determine, is the responsibility of the pump plant. Pay attention to review the tender assembly machine seal is qualified Cartridge machine seal sleeve, seal parts and glands by the complete sets of mechanical seal factory supply, machine seal factory inspection qualified with the positioning plate fixed delivery, mechanical seal installation Easy to ensure quality, packaged in the pump shaft, turn the positioning plate, the mechanical seal axial float, the user does not need any adjustment. Request pump data sheet assembly machine seal, but a lot of bidding pump seal on the shaft sleeve hook sleeve, can not move axially, no positioning plate (container plate). According to Figure 7 a little change to become a genuine container machine seal. Buy chemical pump afraid to be pit to see China's first most complete chemical pump procurement guide and practical experience come out argument ■ tender technical documents should highlight the reliability of the key points and pump reliability and economy. Engineering company common centrifugal pump technical rating should be added to a column "key comments on the ratio of", for each special pump number, the difference between the tender description. Such as the difference between the annual operating costs of high-power pumps; high-power pump bearing type and quantity comparison; large pump NPSH3 and NPSHa benchmark is uniform; NPSH3 and NPSHa the difference is small, the bidder to reduce NPSH3 measures are reliable, Feasible; high-pressure pump axial force comparison, comparison of bearing type and arrangement, reliability analysis of pump economy; delivery of viscous media or suspension pump performance correction is correct. Although this will increase the man-hours of the technical assessment, it is necessary to improve the depth and quality of the technical assessment. [2] Xiang Wei, Xu Yuhu, Zhou Xiaojun, the application of rotary shell pump in the inverter intelligent control system [J]. Chemical Industry Design, 2011, (2), 32-35. [3] China Chemical Engineering Survey and Design Association. "Chemical Design Manual Volume VI (Process Systems Professional)." [4] ANSI / HI9.6.7. Effects of Liquid Viscosity on Rotodynamic (CentrifugalandVertical) Pump Performance [S], 2010. [5] ANSI / HI12.1-12.6.Standard for rotodynamic (centrifugal) slurry pumps. [S], 2011. [6] Chen Yalin. Frequency conversion technology in the centrifugal pump [J]. Petrochemical Technology of Equipment, 2010,31 (2), 40-43. [Editor's note] Hope this article can help the majority of pump procurement executives to open the fog, to find the procurement cost-effective, after-sales service has exceeded expectations of pump manufacturing Manufacturers or distributors. Industrial Internet (Xiamen) Technology Co., Ltd. Asia Pump Network (CEO QQ / WeChat :) Editor: Spring (QQ / WeChat :) (Service Hotline:)