某小區(qū)供熱工程中管網(wǎng)水力計(jì)算與水壓圖分析案例目錄TOC\o"1-3"\h\u20268某小區(qū)供熱工程中管網(wǎng)水力計(jì)算與水壓圖分析案例 139711.1一，二次網(wǎng)的水力計(jì)算 1244541.1.1計(jì)算方法 136051.1.2水力計(jì)算的步驟 1290781.1.3部分管路計(jì)算實(shí)例 2227121.2繪制網(wǎng)路水壓圖 943031.2.1繪制網(wǎng)路水壓圖的必要性 9309121.2.2水壓圖繪制的注意事項(xiàng) 10179841.2.3網(wǎng)路水壓圖的原理及其作用 10276431.2.4繪制水壓圖的原則和要求 11137051.2.5繪制熱水網(wǎng)路水壓圖水壓圖的方法 111.1一，二次網(wǎng)的水力計(jì)算1.1.1計(jì)算方法本設(shè)計(jì)中的水力計(jì)算采用當(dāng)量長度法。1.1.2水力計(jì)算的步驟（1）確定網(wǎng)路中熱媒的計(jì)算流量（4-1）式中—供暖系統(tǒng)用戶的計(jì)算流量，T/h；/—一次網(wǎng)的設(shè)計(jì)供回水溫度，℃。—用戶熱負(fù)荷，KW；—水的比熱，取=1.187KJ/Kg·℃；（2）利用所查知識確定熱水網(wǎng)路的主干線走向以及主干線的沿程比摩阻，通過查閱《城市熱力網(wǎng)設(shè)計(jì)規(guī)范》可得比摩阻R的取值范圍大概在30-70Pa/m，此時該管內(nèi)流速不能超過3.5m/s。（3要想確定主干線個管段的公稱直徑和與公稱直徑對應(yīng)的實(shí)際比摩阻，就得根據(jù)網(wǎng)路主干線各個管段的流量和第一次選定的R值，翻閱參考文獻(xiàn)。根據(jù)上述步驟中確定的公稱直徑和管中局部阻力，計(jì)算管段局部阻力相當(dāng)長度Ld及折合長度Lzh。（5）選定好各管段折算長度Lzh后，利用它們的總和計(jì)算各管段壓降△P。（4-2）式中—管段壓降，Pa；—局部阻力當(dāng)量長度。—管段的實(shí)際長度，m?！芏蔚膶?shí)際比摩阻，Pa。確定主干線的管徑后，支管管徑的計(jì)算類比上式。同時，對于一、二次網(wǎng)的支線比摩阻不能大于300Pa/m。必須保證各并聯(lián)管路的壓降大致相等，從而盡可能促成系統(tǒng)網(wǎng)路中各用戶的水力平衡，不滿足上述條件時，我們需要通過安裝調(diào)節(jié)閥門來使管道平衡，降低其不平衡率。根據(jù)青島市翻斗花園小區(qū)熱力站供熱區(qū)域建筑的負(fù)荷，按照面積指標(biāo)法計(jì)算結(jié)果即可進(jìn)行該熱網(wǎng)的水力計(jì)算。系統(tǒng)分為南、北兩個區(qū)，需要對其分別進(jìn)行計(jì)算。1.1.3部分管路計(jì)算實(shí)例1）計(jì)算設(shè)計(jì)流量。南區(qū)主干線管線11計(jì)算的熱負(fù)荷為3630000W；下面以管段11為例： （2）計(jì)算管網(wǎng)主干線的其余參數(shù)根青島市小區(qū)熱力站管線平面圖可以看出,從換熱站到最遠(yuǎn)居民樓的管線是主干線，主干線包括管線1，3，5，7，9，11。主干線11是從熱力站出來后的第一根管線，其要包括整個南區(qū)的所有流量，即管線1的流量G1=312.3t/h；根據(jù)南區(qū)主干管1-11計(jì)算的流量和30-70的R值范圍，可以假定低區(qū)主干管1的管徑和相應(yīng)的比摩阻R值,即DN=300mm；R=58Pa/m。將下列南區(qū)主管內(nèi)的局部阻力分量換算為等效長度，當(dāng)標(biāo)稱供熱管直徑為≤400mm時，沿程估計(jì)的局部損耗比和損耗為Aj=0.3。則南區(qū)主干管1-11的折算長度和壓降由下式求得:=mPa南區(qū)水力計(jì)算表4-1水管水力計(jì)算編號負(fù)荷W流量kg/h管徑管長mv(m/s)R(Pa/m)Py(Pa)Pj(Pa)Py+Pj(Pa)19630008281818019.90.904581151.2346.261500.462247500212858015.91.1762694277.11283.135560.2331.21E+0610410319026.50.92521378413.41791.449630008281814012.61.4942122671.2801.363472.5652.17E+061869212406.81.14764435.2130.56565.7662475002128580161.17526943041291.25595.272.42E+0620820625025.81.178651677503.12180.189630008281814012.31.4942122607.6782.283389.8893.38E+0629102428071.31269483141.9627.910247500212858016.21.1752694357.81307.345665.14113.63E+0631230929041.51.313672780.5831.153611.65北區(qū)水力計(jì)算表4-2122475002128511035.90.622511830.9549.272380.17139630008281814010.41.4942122201.8661.442866.24141.21E+0610410319013.91.01968945.2283.561228.7615247500212858016.81.1752694519.21355.765871.96161.46E+0612538821019.91.008591171.1352.231526.33179630008281814012.21.4942122586.4775.923362.32182.42E+0620820625013.31.17865861.5259.351123.8519247500212858015.61.1752694196.41258.925455.32202.67E+0622949126020.81.200641331.2399.361730.56217875006772512013.11.5162653471.51041.454512.95223.46E+0629721629011.71.24960882261.61146.623247500212858015.61.1712674165.21249.565411.76243.70E+0631850129091.61.339696320.41896.128216.52用同樣的方法，可計(jì)算主干線其余管段，確定其管徑和壓力損失。具體結(jié)果見表4-3和4-4。南區(qū)支線水力計(jì)算表4-3編號負(fù)荷W流量t/h管徑管長mv(m/s)R(Pa/m)Py(Pa)Pj(Pa)Py+Pj(Pa)1a77040066.2420019.370.58621406.77122.031528.8011b57780049.6815022.610.78541220.94366.2821587.2221c38520033.1212515.740.74963991.62297.4861289.1061d19260016.5610022.030.586511123.53337.0591460.5892a16500011.198011.470.7841201736.4520.922257.322b825007.098020.570.39131637.67191.301828.9714a77040066.2415019.371.041961859.52557.8562417.3764b57780049.6812522.611.1411242803.64841.0923641.7324c38520033.1210015.741.1712023179.48953.8444133.3244d19260016.568022.030.9151633590.891077.2674668.1576a16500011.198011.470.7841201736.4520.922257.326b825007.098020.570.39131637.67191.301828.9718a77040066.2415019.371.041961859.52557.8562417.3768b57780049.6812522.611.1411242803.64841.0923641.7328c38520033.1210015.741.1712023179.48953.8444133.3248d19260016.568022.030.9151633590.891077.2674668.15710a16500011.198011.470.7841201736.4520.922257.3210b825007.098020.570.39131637.67191.301828.971北區(qū)支線水力計(jì)算表4-4編號負(fù)荷W流量t/h管徑管長mv(m/s)R(Pa/m)Py(Pa)Pj(Pa)Py+Pj(Pa)12a16500011.1910011.470.50238549.86161.958711.81812b825007.098020.570.39131637.67191.301828.97113a77040066.2415016.281.041961562.88468.8642031.74413b57780049.6812515.41.1411241909.6572.882482.4813c38520033.1210022.721.1712024589.441376.8325966.27213d19260016.568025.270.9151634119.011235.7035351.71315a16500011.198011.470.7841201736.4520.922257.3215b825007.098020.570.39131637.67191.301828.97117a77040066.2415019.91.041961910.4573.122483.5217b57780049.6812522.591.1411242801.16840.3483641.50817c38520033.1210015.671.1712023165.34949.6024111.94217d19260016.568021.610.9151633522.431056.7294579.15919a16500011.198011.470.7841201736.4520.922257.3219b825007.098020.570.39131637.67191.301828.97121a59062550.7912516.861.1491472478.42743.5263221.94621b39375033.8610022.491.1972114745.391423.6176169.00721c19687516.938022.780.9351713895.381168.6145063.99423a16500011.198011.470.7841201736.4520.922257.3223b825007.098020.570.39131637.67191.301828.971同上述要求可計(jì)算得一次網(wǎng)的管徑見表4-5一次網(wǎng)水力計(jì)算表4-5編號負(fù)荷W流量t/h管徑管長mv(m/s)R(Pa/m)Py(Pa)Pj(Pa)Py+Pj(Pa)1720000061920030085.42.4221718531.85559.5424091.34272000006192004002331.3749114173425.114842.13810000069660030038.32.7427410491.23148.2613642.464153000001315800600411.29261066319.81385.85225000001935000600801.9564480134458246675000058050030022.82.2819043321299.65631.6729250000251550070013.51.8242567170.1737.18720000061920030017.62.432173819.21145.764961.96936450000313470070060.32.26653919.51175.855095.35107200000619200300151.52.4321733526.510057.9543581.4511436500003753900800207.42.07469540.42862.1212402.52一次網(wǎng)水力計(jì)算表4-51.2繪制網(wǎng)路水壓圖1.2.1繪制網(wǎng)路水壓圖的必要性熱網(wǎng)中有許多熱用戶。他們處在在不同的地形。而且由于不同用戶不一樣的用水習(xí)慣，可能會導(dǎo)致系統(tǒng)壓力和溫度發(fā)生改變。在設(shè)計(jì)的時候，整個管網(wǎng)的壓力狀況是一致的，必須單獨(dú)拿出來考慮，但水力計(jì)算只能算出熱水管道中各個管段的壓降，不能確定熱水供暖系統(tǒng)中各個用戶點(diǎn)的壓力。所以，我們通過制作熱水管網(wǎng)水壓圖，這樣的話就可以知道熱水經(jīng)過哪些用戶的壓頭損失是多少。從而保證了水力平衡技術(shù)措施的實(shí)現(xiàn)。在運(yùn)行中，要想直接了解整個系統(tǒng)在調(diào)節(jié)過程中的情況，可以從管網(wǎng)的實(shí)際水壓圖得知。每個用戶怎么連接到系統(tǒng)中，還有供熱系統(tǒng)的自控裝置的選擇也要依據(jù)管網(wǎng)的壓力。通過查看水壓圖，可以找出關(guān)鍵問題，采取必要的技術(shù)措施。通俗的說，水壓圖就是指定決策時的依據(jù)。1.2.2水壓圖繪制的注意事項(xiàng)水壓圖的繪制，要考慮到建筑物的地理標(biāo)高，同時也要考慮到處于該位置下系統(tǒng)是否會出現(xiàn)超壓問題。我們將繪制水壓圖時的注意事項(xiàng)稱為“四不一滿”：不超壓、不汽化、不倒空、不吸氣，保證循環(huán)。從安全角度來看，應(yīng)預(yù)留30-50kpa的富裕壓力值。其余氣化、吸氣等條件的出現(xiàn)在此次設(shè)計(jì)中可以不予考慮。繪制水壓圖后，我們可以仔細(xì)明確熱水管網(wǎng)和所有熱用戶的壓力情況。同時，通過對管道水壓圖的分析，可以了解管道的連接形態(tài)，并確保供水系統(tǒng)功能的安全運(yùn)行。1.2.3網(wǎng)路水壓圖的原理及其作用1.2.3.1原理水壓圖是根據(jù)伯努利方程原理繪制的，即1.2.2.2作用（1）根據(jù)水壓曲線的梯度，可以確定單位長度管道的平均壓降。（2）管道上其他點(diǎn)的壓力是根據(jù)已知任意一點(diǎn)的壓力確定的（3）利用水壓曲線可以確定管道中任意一點(diǎn)的壓力值。（4）壓力曲線可以用來表示各管段的阻力損失。1.2.4繪制水壓圖的原則和要求（1）供回水管道的壓降應(yīng)滿足換熱站和熱用戶所需的資用壓頭之和（2）管網(wǎng)回流管中的任何壓力點(diǎn)應(yīng)至少要高于大氣壓力5mh2o，以避免空氣進(jìn)入系統(tǒng)中造成故障。（3）在高溫水網(wǎng)和用戶系統(tǒng)中特別要注意防止汽化，對溫度超過100℃的點(diǎn)處的壓力必須大于在100℃下的汽化壓力，否則將會產(chǎn)生汽化腐蝕管道。（4）當(dāng)水泵直接與熱水管網(wǎng)連接時，為了防止產(chǎn)生倒吸現(xiàn)象，破壞管道的正常運(yùn)行和腐蝕。不管在什么情況下，用戶系統(tǒng)回水管出口壓力必須高于配套系統(tǒng)的靜水壓